Nails and nail varnish: Brussels bombers prepared a 'satanic' cocktail

Before you go, we thought you'd like these...
Before you go close icon

TATP Explosives Likely Used in Brussels Attacks

BRUSSELS (Reuters) -- An empty apartment block on a quiet street turned out to be the perfect place for the three suspected Brussels attackers to prepare the home-made nail bombs used in Tuesday's airport and metro attacks that killed at least 31 people.

READ MORE: Brussels attacks survivor Mason Wells speaks out

In a building undergoing renovation, there were no near neighbors to notice them taking in large quantities of strong-smelling household chemicals, as well as a suitcase of nails, to concoct an unstable white explosive powder known as TATP, or triacetone triperoxide, that they later used in their attacks.

RELATED: Memorials following the deadly blasts in Brussels

58 PHOTOS
Memorials in Brussels after attacks
See Gallery
Nails and nail varnish: Brussels bombers prepared a 'satanic' cocktail
People holding a banner reading "I am Brussels" behind flowers and candles to mourn for the victims at Place de la Bourse in the center of Brussels, Tuesday, March 22, 2016. Bombs exploded at the Brussels airport and one of the city's metro stations Tuesday, killing and wounding scores of people, as a European capital was again locked down amid heightened security threats. (AP Photo/Martin Meissner)
Young women hold each other at a makeshift memorial in front of the stock exchange at the Place de la Bourse (Beursplein) in Brussels on March 22, 2016, following triple bomb attacks in the Belgian capital that killed about 35 people and left more than 200 people wounded. A series of explosions claimed by the Islamic State group ripped through Brussels airport and a metro train on March 22, killing around 35 people in the latest attacks to bring bloody carnage to the heart of Europe. AFP PHOTO / KENZO TRIBOUILLARD / AFP / KENZO TRIBOUILLARD (Photo credit should read KENZO TRIBOUILLARD/AFP/Getty Images)
People bring flowers and candles to mourn at the Place de la Bourse in the center of Brussels, Tuesday, March 22, 2016. Bombs exploded at the Brussels airport and one of the city's metro stations Tuesday, killing and wounding scores of people, as a European capital was again locked down amid heightened security threats. (AP Photo/Martin Meissner)
BRUSSELS, BELGIUM - MARCH 22: People gather at Place de la Bourse in support of the victims after the terrorist attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Aurelien Meunier/Getty Images)
TOPSHOT - A photo taken on March 22, 2016 shows a sign peace made of candles in front of the Bourse of Brussels in tribute to the victims of Brussels following triple bomb attacks in the Belgian capital that killed about 35 people and left more than 200 people wounded. Belgium launched a huge manhunt on March 22 after a series of bombings claimed by the Islamic State group ripped through Brussels airport and a metro train, killing around 35 people in the latest attack to bring carnage to the heart of Europe. / AFP / BELGA / Aurore Belot / Belgium OUT (Photo credit should read AURORE BELOT/AFP/Getty Images)
TOPSHOT - People light candles in tribute to victims at a makeshift memorial in front of the stock exchange at the Place de la Bourse (Beursplein) in Brussels on March 22, 2016, following triple bomb attacks in the Belgian capital that killed about 35 people and left more than 200 people wounded. A series of explosions claimed by the Islamic State group ripped through Brussels airport and a metro train on March 22, killing around 35 people in the latest attacks to bring bloody carnage to the heart of Europe. AFP PHOTO / KENZO TRIBOUILLARD / AFP / KENZO TRIBOUILLARD (Photo credit should read KENZO TRIBOUILLARD/AFP/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: A young girl lights a candle at the Place de la Bourse following today's attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Carl Court/Getty Images)
TOPSHOT - People stand hand in hand in tribute to victims at a makeshift memorial in front of the stock exchange at the Place de la Bourse (Beursplein) in Brussels on March 22, 2016, following triple bomb attacks in the Belgian capital that killed about 35 people and left more than 200 people wounded. A series of explosions claimed by the Islamic State group ripped through Brussels airport and a metro train on March 22, killing around 35 people in the latest attacks to bring bloody carnage to the heart of Europe. AFP PHOTO / KENZO TRIBOUILLARD / AFP / KENZO TRIBOUILLARD (Photo credit should read KENZO TRIBOUILLARD/AFP/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: People gather to leave tributes at the Place de la Bourse following today's attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Carl Court/Getty Images)
A message written on the ground reads 'Brussels is beautiful' next to flowers and candles following attacks in Brussels on March 22, 2016. Airlines cancelled hundreds of flights and European railways froze links with Brussels after a series of bomb blasts killed around 35 people in the city's airport and a metro train, sparking a broad security response. AFP PHOTO / KENZO TRIBOUILLARD / AFP / KENZO TRIBOUILLARD (Photo credit should read KENZO TRIBOUILLARD/AFP/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: People gather at Place de la Bourse in support of the victims after the terrorist attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Aurelien Meunier/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: People gather at Place de la Bourse in support of the victims after the terrorist attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Aurelien Meunier/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: People gather at Place de la Bourse in support of the victims after the terrorist attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Aurelien Meunier/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: People gather at Place de la Bourse in support of the victims after the terrorist attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Aurelien Meunier/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: People gather at Place de la Bourse in support of the victims after the terrorist attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Aurelien Meunier/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: People gather at Place de la Bourse in support of the victims after the terrorist attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Aurelien Meunier/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: People gather at Place de la Bourse in support of the victims after the terrorist attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Aurelien Meunier/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: People gather at Place de la Bourse in support of the victims after the terrorist attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Aurelien Meunier/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: People gather at Place de la Bourse in support of the victims after the terrorist attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Aurelien Meunier/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: People gather at Place de la Bourse in support of the victims after the terrorist attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Aurelien Meunier/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: People gather at Place de la Bourse in support of the victims after the terrorist attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Aurelien Meunier/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: People gather at Place de la Bourse in support of the victims after the terrorist attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Aurelien Meunier/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: People gather at Place de la Bourse in support of the victims after the terrorist attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Aurelien Meunier/Getty Images)
People bring flowers and candles to mourn at the Place de la Bourse in the center of Brussels, Tuesday, March 22, 2016. Bombs exploded at the Brussels airport and one of the city's metro stations Tuesday, killing and wounding scores of people, as a European capital was again locked down amid heightened security threats. (AP Photo/Martin Meissner)
BRUSSELS, BELGIUM - MARCH 22: People light candles at the Place de la Bourse following today's attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Carl Court/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: People hold up a banner as a mark of solidarity at the Place de la Bourse following today's attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Carl Court/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: Candles are lit at the Place de la Bourse following today's attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Carl Court/Getty Images)
People bring flowers and candles to mourn for the victims at Place de la Bourse in the center of Brussels, Tuesday, March 22, 2016. Bombs exploded at the Brussels airport and one of the city's metro stations Tuesday, killing and wounding scores of people, as a European capital was again locked down amid heightened security threats. (AP Photo/Martin Meissner)
People mourn for the victims at Place de la Bourse in the center of Brussels, Tuesday, March 22, 2016. Bombs exploded at the Brussels airport and one of the city's metro stations Tuesday, killing and wounding scores of people, as a European capital was again locked down amid heightened security threats. (AP Photo/Martin Meissner)
A placard reads 'Share your love' at a makeshift memorial following attacks in Brussels on March 22, 2016. Airlines cancelled hundreds of flights and European railways froze links with Brussels after a series of bomb blasts killed around 35 people in the city's airport and a metro train, sparking a broad security response. AFP PHOTO / KENZO TRIBOUILLARD / AFP / KENZO TRIBOUILLARD (Photo credit should read KENZO TRIBOUILLARD/AFP/Getty Images)
Writing on the asphalt reads "More stars in Brussel's heaven" at Place de la Bourse in the center of Brussels, where people write hundreds of messages on the ground to remember the victims of Tuesday's attack, Tuesday, March 22, 2016. Bombs exploded at the Brussels airport and one of the city's metro stations Tuesday, killing and wounding scores of people, as a European capital was again locked down amid heightened security threats. (AP Photo/Martin Meissner)
A woman reads messages written on the ground at Place de la Bourse (Beursplein) following attacks in Brussels on March 22, 2016. Airlines cancelled hundreds of flights and European railways froze links with Brussels after a series of bomb blasts killed around 35 people in the city's airport and a metro train, sparking a broad security response. AFP PHOTO / KENZO TRIBOUILLARD / AFP / KENZO TRIBOUILLARD (Photo credit should read KENZO TRIBOUILLARD/AFP/Getty Images)
People walk over messages written on the ground at Place de la Bourse (Beursplein) following attacks in Brussels on March 22, 2016. Airlines cancelled hundreds of flights and European railways froze links with Brussels after a series of bomb blasts killed around 35 people in the city's airport and a metro train, sparking a broad security response. AFP PHOTO / KENZO TRIBOUILLARD / AFP / KENZO TRIBOUILLARD (Photo credit should read KENZO TRIBOUILLARD/AFP/Getty Images)
People leave candles and flowers in tribute to victims of triple bomb attacks in front of the stock exchange building in the city center of Brussels on March 22, 2016. A series of apparently coordinated explosions ripped through Brussels airport and a metro train, killing at least 26 people in the latest attacks to target Europe. / AFP / Belga / NICOLAS MAETERLINCK / Belgium OUT (Photo credit should read NICOLAS MAETERLINCK/AFP/Getty Images)
People leave messages and flowers in tribute to victims of triple bomb attacks in front of the stock exchange building in the city center of Brussels on March 22, 2016. A series of apparently coordinated explosions ripped through Brussels airport and a metro train, killing at least 26 people in the latest attacks to target Europe. / AFP / Belga / NICOLAS MAETERLINCK / Belgium OUT (Photo credit should read NICOLAS MAETERLINCK/AFP/Getty Images)
People gather around a makeshift memorial at Place de la Bourse (Beursplein) following attacks in Brussels on March 22, 2016. Airlines cancelled hundreds of flights and European railways froze links with Brussels after a series of bomb blasts killed around 35 people in the city's airport and a metro train, sparking a broad security response. AFP PHOTO / KENZO TRIBOUILLARD / AFP / KENZO TRIBOUILLARD (Photo credit should read KENZO TRIBOUILLARD/AFP/Getty Images)
A placard reads share your love next to flowers and candles laid on the ground following attacks in Brussels on March 22, 2016. Airlines cancelled hundreds of flights and European railways froze links with Brussels after a series of bomb blasts killed around 35 people in the city's airport and a metro train, sparking a broad security response. AFP PHOTO / KENZO TRIBOUILLARD / AFP / KENZO TRIBOUILLARD (Photo credit should read KENZO TRIBOUILLARD/AFP/Getty Images)
A man looks at flowers and messages outside the stock exchange in Brussels on Tuesday, March 22, 2016. Explosions, at least one likely caused by a suicide bomber, rocked the Brussels airport and subway system Tuesday, prompting a lockdown of the Belgian capital and heightened security across Europe. At least 26 people were reported dead. (AP Photo/Geert Vanden Wijngaert)
A woman places candles in the shape of a heart outside the stock exchange in Brussels on Tuesday, March 22, 2016. Explosions, at least one likely caused by a suicide bomber, rocked the Brussels airport and subway system Tuesday, prompting a lockdown of the Belgian capital and heightened security across Europe. At least 26 people were reported dead. (AP Photo/Geert Vanden Wijngaert)
Solidarity messages are written in chalk outside the stock exchange in Brussels on Tuesday, March 22, 2016. Explosions, at least one likely caused by a suicide bomber, rocked the Brussels airport and subway system Tuesday, prompting a lockdown of the Belgian capital and heightened security across Europe. At least 26 people were reported dead. (AP Photo/Geert Vanden Wijngaert)
A heart in the colours of the Belgian flag is taped onto a bag as people gather around a makeshift memorial following attacks in Brussels on March 22, 2016. Airlines cancelled hundreds of flights and European railways froze links with Brussels after a series of bomb blasts killed around 35 people in the city's airport and a metro train, sparking a broad security response. AFP PHOTO / KENZO TRIBOUILLARD / AFP / KENZO TRIBOUILLARD (Photo credit should read KENZO TRIBOUILLARD/AFP/Getty Images)
People write messages on the ground at Place de la Bourse (Beursplein) following attacks in Brussels on March 22, 2016. Airlines cancelled hundreds of flights and European railways froze links with Brussels after a series of bomb blasts killed around 35 people in the city's airport and a metro train, sparking a broad security response. AFP PHOTO / KENZO TRIBOUILLARD / AFP / KENZO TRIBOUILLARD (Photo credit should read KENZO TRIBOUILLARD/AFP/Getty Images)
A man writes the word 'Peace' in different languages at Place de la Bourse (Beursplein) following attacks in Brussels on March 22, 2016. Airlines cancelled hundreds of flights and European railways froze links with Brussels after a series of bomb blasts killed around 35 people in the city's airport and a metro train, sparking a broad security response. AFP PHOTO / KENZO TRIBOUILLARD / AFP / KENZO TRIBOUILLARD (Photo credit should read KENZO TRIBOUILLARD/AFP/Getty Images)
Two people write solidarity messages in chalk outside the stock exchange in Brussels on Tuesday, March 22, 2016. Explosions, at least one likely caused by a suicide bomber, rocked the Brussels airport and subway system Tuesday, prompting a lockdown of the Belgian capital and heightened security across Europe. At least 26 people were reported dead. (AP Photo/Geert Vanden Wijngaert)
A man walks by solidarity messages written in chalk outside the stock exchange in Brussels on Tuesday, March 22, 2016. Explosions, at least one likely caused by a suicide bomber, rocked the Brussels airport and subway system Tuesday, prompting a lockdown of the Belgian capital and heightened security across Europe. At least 26 people were reported dead. (AP Photo/Geert Vanden Wijngaert)
A replica of the Manneken Pis statue stands at a makeshift memorial at Place de la Bourse (Beursplein) following attacks in Brussels on March 22, 2016. Airlines cancelled hundreds of flights and European railways froze links with Brussels after a series of bomb blasts killed around 35 people in the city's airport and a metro train, sparking a broad security response. AFP PHOTO / KENZO TRIBOUILLARD / AFP / KENZO TRIBOUILLARD (Photo credit should read KENZO TRIBOUILLARD/AFP/Getty Images)
People hold hands as they gather at a makeshift memorial at Place de la Bourse (Beursplein) following attacks in Brussels on March 22, 2016. Airlines cancelled hundreds of flights and European railways froze links with Brussels after a series of bomb blasts killed around 35 people in the city's airport and a metro train, sparking a broad security response. AFP PHOTO / KENZO TRIBOUILLARD / AFP / KENZO TRIBOUILLARD (Photo credit should read KENZO TRIBOUILLARD/AFP/Getty Images)
People hold hands as they gather at a makeshift memorial at Place de la Bourse (Beursplein) following attacks in Brussels on March 22, 2016. Airlines cancelled hundreds of flights and European railways froze links with Brussels after a series of bomb blasts killed around 35 people in the city's airport and a metro train, sparking a broad security response. AFP PHOTO / KENZO TRIBOUILLARD / AFP / KENZO TRIBOUILLARD (Photo credit should read KENZO TRIBOUILLARD/AFP/Getty Images)
People light candles at a makeshift memorial at Place de la Bourse (Beursplein) following attacks in Brussels on March 22, 2016. Airlines cancelled hundreds of flights and European railways froze links with Brussels after a series of bomb blasts killed around 35 people in the city's airport and a metro train, sparking a broad security response. AFP PHOTO / KENZO TRIBOUILLARD / AFP / KENZO TRIBOUILLARD (Photo credit should read KENZO TRIBOUILLARD/AFP/Getty Images)
A replica of the Manneken Pis statue is placed among candles at a makeshift memorial at Place de la Bourse (Beursplein) following attacks in Brussels on March 22, 2016. Airlines cancelled hundreds of flights and European railways froze links with Brussels after a series of bomb blasts killed around 35 people in the city's airport and a metro train, sparking a broad security response. AFP PHOTO / KENZO TRIBOUILLARD / AFP / KENZO TRIBOUILLARD (Photo credit should read KENZO TRIBOUILLARD/AFP/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: People walk across slogans written on the ground in chalk saying 'Brussels, Belgium, Today' at Beursplein sqaure following todays attack on March 22, 2016 in Brussels, Belgium. At least 34 people are thought to have been killed after Brussels airport and the Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. on March 22, 2016 in Brussels, Belgium. (Photo by Alexander Koerner/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: A painting is left as a tribute at the Place de la Bourse following today's attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Carl Court/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: A message is written on a wall following today's attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Carl Court/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: Flowers are placed into the mouth of a lion statue as people gather to leave tributes at the Place de la Bourse following today's attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Carl Court/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: A candle is lit as people gather to leave tributes at the Place de la Bourse following today's attacks on March 22, 2016 in Brussels, Belgium. At least 31 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Carl Court/Getty Images)
A man lights a candle next to the iconic statue of Manneken Pis outside the stock exchange in Brussels on Tuesday, March 22, 2016. Explosions, at least one likely caused by a suicide bomber, rocked the Brussels airport and subway system Tuesday, prompting a lockdown of the Belgian capital and heightened security across Europe. (AP Photo/Geert Vanden Wijngaert)
A memorial to attack victims with a Belgian flag and flowers is set up outside the stock exchange in Brussels on Tuesday, March 22, 2016. Explosions, at least one likely caused by a suicide bomber, rocked the Brussels airport and subway system Tuesday, prompting a lockdown of the Belgian capital and heightened security across Europe. (AP Photo/Geert Vanden Wijngaert)
of
SEE ALL
BACK TO SLIDE
SHOW CAPTION +
HIDE CAPTION

"Even if someone had stopped them, they could have said the materials were for renovation," said Hassan Abid, an official at the local town hall, who was trying to determine why authorities had no knowledge of the men living illegally on the fifth floor.

Belgian investigators do not answer questions on the case.

Having moved in two months ago, the Belgian brothers Khalid and Brahim El Bakraoui used the apartment in the largely middle class borough of Schaerbeek as a laboratory-cum-hideout, from where Brahim and two other men took a taxi on Tuesday morning to the airport to commit their attacks.

Their choice of low-cost explosives -- among ingredients are drain cleaner and nail varnish remover -- apparent knowledge of chemistry and ability to set up in an apartment 15 minutes drive from the airport should offer clues about IS bombmaking methods to investigators struggling to understand how the Syria-based group built a violent network of radicalized young Belgians.

RELATED: International response to the Brussels attacks

34 PHOTOS
Brussels Attacks: International security response
See Gallery
Nails and nail varnish: Brussels bombers prepared a 'satanic' cocktail
PARIS, FRANCE - MARCH 22: (FRANCE OUT) French police officers patrol at the Trocadero Plaza next to the Eiffel Tower on March 22, 2106 in Paris, France. Since this morning 400 policemen and gendarmes have been deployed to increase the security in airports, stations and public transportation around Paris and its region after the terrorist attacks in Brussels today. (Photo by Christophe Morin/IP3/Getty Images)
German police officers guard a terminal of the airport in Frankfurt, Germany, Tuesday, March 22, 2016, when various explosions hit the Belgian capital Brussels killing several people. (AP Photo/Michael Probst)
An Israeli airport security guard patrols with a dog in Ben Gurion airport near Tel Aviv, Israel, Tuesday, March 22, 2016. After the Brussels attacks, Israel briefly announced that all Israeli flights from Europe were canceled, then reinstated the flights, Israel Airports Authority spokesman Ofer Leffler said. Pini Schiff, former director of security at Ben-Gurion Airport, said the attack in the Brussels airport was âa colossal failureâ of Belgian security, and he said âthe chances are very lowâ that such a bombing could take place in Israelâs airport. Israel's Ben-Gurion Airport is considered among the most secure in the world, an outcome stemming from several Palestinian attacks on Israeli planes and travelers in the 1970s. (AP Photo/Ariel Schalit)
A police officer guards a terminal of the airport during tighter security measures in Barcelona, Spain, Tuesday, March 22, 2016. Explosions, at least one likely caused by a suicide bomber, rocked the Brussels airport and subway system Tuesday, prompting a lockdown of the Belgian capital and heightened security across Europe. (AP Photo/Emilio Morenatti)
Travelers wait at the counter of Brussels airlines in Ben Gurion airport near Tel Aviv, Israel, Tuesday, March 22, 2016. After the Brussels attacks, Israel briefly announced that all Israeli flights from Europe were canceled, then reinstated the flights, Israel Airports Authority spokesman Ofer Leffler said. Pini Schiff, former director of security at Ben-Gurion Airport, said the attack in the Brussels airport was âa colossal failureâ of Belgian security, and he said âthe chances are very lowâ that such a bombing could take place in Israelâs airport. Israel's Ben-Gurion Airport is considered among the most secure in the world, an outcome stemming from several Palestinian attacks on Israeli planes and travelers in the 1970s. (AP Photo/Ariel Schalit)
An Israeli airport security guard patrols with a dog in Ben Gurion airport near Tel Aviv, Israel, Tuesday, March 22, 2016. After the Brussels attacks, Israel briefly announced that all Israeli flights from Europe were canceled, then reinstated the flights, Israel Airports Authority spokesman Ofer Leffler said. Pini Schiff, former director of security at Ben-Gurion Airport, said the attack in the Brussels airport was âa colossal failureâ of Belgian security, and he said âthe chances are very lowâ that such a bombing could take place in Israelâs airport. Israel's Ben-Gurion Airport is considered among the most secure in the world, an outcome stemming from several Palestinian attacks on Israeli planes and travelers in the 1970s. (AP Photo/Ariel Schalit)
French soldiers check unattended boxes left on the platform at Gare De Lyon railway station in Paris, France, Tuesday, March 22, 2016. Authorities are tightening security at airports and on the streets of European cities after attacks on the Brussels airport and subways system that killed at least one person and injured many others. (AP Photo/Francois Mori)
Passengers of an ICE train leave the train at its final stop at the station in Aachen, Germany, near to the Belgian border Tuesday March 22, 2016. German police have increased security measures at the borders following the terrorist attacks in Brussels. (Ralf Roeger/dpa via AP)
Passengers at Warsawâs Frederic Chopin airport in Warsaw, Poland on Tuesday, March 22, 2016, pass by an information board that lists flights to Brussels as canceled, following deadly blasts at Busselsâ airport. (AP Photo/Czarek Sokolowski)
A German police officer guards a terminal of the airport in Frankfurt, Germany, Tuesday, March 22, 2016, when various explosions hit the Belgian capital Brussels killing several people. (AP Photo/Michael Probst)
Border guards patrol at Warsawâs Frederic Chopin airport in Warsaw, Poland on Tuesday, March 22, 2016 after security measures were increased at Polandâs airports following attacks in Brussels , Belgium. (AP Photo/Czarek Sokolowski)
Border Guards patrol at Warsawâs Frederic Chopin airport in Warsaw, Poland on Tuesday, March 22, 2016 after security measures were increased at Polandâs airports following attacks in Brussels , Belgium. (AP Photo/Czarek Sokolowski)
French police officers patrol outside the Gare du Nord train station, where high speed trains depart to Brussels, in Paris, Tuesday, March 22, 2016. Authorities in Europe and across the world tightened security at airports, railway stations, government buildings and other key points after deadly attacks Tuesday on the Brussels airport and its subway system. (AP Photo/Francois Mori)
PARIS, FRANCE - MARCH 22: (FRANCE OUT) French police officers patrol at the Trocadero Plaza next to the Eiffel Tower on March 22, 2106 in Paris, France. Since this morning 400 policemen and gendarmes have been deployed to increase the security in airports, stations and public transportation around Paris and its region after the terrorist attacks in Brussels today. (Photo by Christophe Morin/IP3/Getty Images)
A police officer with a sniffer dog checks a trash bin at the airport in Prague, Czech Republic, Tuesday, March 22, 2016. Authorities in Europe have tightened security at airports, on subways, at the borders and on city streets after deadly attacks Tuesday on the Brussels airport and its subway system. (AP Photo/Petr David Josek)
Danish police patrol Copenhagen International Airport, in Kastrup, Denmark, Tuesday, March 22, 2016. Authorities in Europe have tightened security at airports, on subways, at the borders and on city streets after deadly attacks Tuesday on the Brussels airport and its subway system. (Jens Dresling/POLFOTO via AP) DENMARK OUT
An electronic billboard displays two canceled flight to Brussels at Milan's Malpensa international airport, in Busto Arsizio, Italy, Tuesday, March 22, 2016. Authorities in Europe have tightened security at airports, on subways, at the borders and on city streets after deadly attacks Tuesday on the Brussels airport and its subway system. (AP Photo/Luca Bruno)
An armed British policeman stands on duty outside as tourists walk past Horse Guards parade in central London, Tuesday, March 22, 2016. Authorities in Europe and beyond have tightened security at airports, on subways, at the borders and on city streets after deadly attacks Tuesday on the Brussels airport and its subway system. (AP Photo/Alastair Grant)
London's Metropolitan Police Commissioner Bernard Hogan-Howe leaves the Cabinet Office in London, after a government emergency meeting in the wake of the attacks in Brussels, Tuesday, March, 22, 2016. Authorities in Europe and beyond have tightened security at airports, on subways, at the borders and on city streets after deadly attacks Tuesday on the Brussels airport and its subway system. (AP Photo/Alastair Grant)
Police officers patrol the check in area of the Milan's Malpensa international airport, in Busto Arsizio, Italy, Tuesday, March 22, 2016. Authorities in Europe have tightened security at airports, on subways, at the borders and on city streets after deadly attacks Tuesday on the Brussels airport and its subway system. (AP Photo/Luca Bruno)
A Eurostar train arrivals board shows the Brussels route is cancelled due to "Security Alert in Brussels", at St Pancras international railway station in London, Tuesday, March 22, 2016. Authorities in Europe and beyond have tightened security at airports, on subways, at the borders and on city streets after deadly attacks Tuesday on the Brussels airport and its subway system. (AP Photo/Matt Dunham)
Italian police officers patrol Leonardo Da Vinci airport in Fiumicino, near Rome, Tuesday, March 22, 2016. Authorities in Europe and beyond have tightened security at airports, on subways, at the borders and on city streets after deadly attacks Tuesday on the Brussels airport and its subway system. (AP Photo/Alessandra Tarantino)
A Italian police dog sniffs passengers' luggage at Leonardo Da Vinci airport in Fiumicino, near Rome, Tuesday, March 22, 2016. Authorities in Europe and beyond have tightened security at airports, on subways, at the borders and on city streets after deadly attacks Tuesday on the Brussels airport and its subway system. (AP Photo/Alessandra Tarantino)
A member of the Counter Terrorism Centre (TEK) patrols the area in front of the Parliament in downtown Budapest, Hungary, Tuesday, March 22, 2016. Hungary raised its terrorism awareness level to grade 2 after a series of attacks in Brussels. (Zoltan Balogh/MTI via AP)
German police officers guard a terminal of the airportthe in Frankfurt, Germany, during tighter security measures Tuesday, March 22, 2016, when various explosions hit the Belgian capital Brussels killing several people. (AP Photo/Michael Probst)
Counter Terrorism Centre (TEK) personnel arrive with an APC vehicle at the parking facility of the Liszt Ferenc International Airport in Budapest, Hungary, Tuesday, March 22, 2016. Hungary raised its terrorism awareness level to grade 2 after a series of attacks in Brussels. (Zsolt Szigetvary/MTI via AP)
French soldier patrols in Gare De Lyon railway station in Paris, France, Tuesday, March 22, 2016. Authorities are tightening security at airports and on the streets of European cities after attacks on the Brussels airport and subways system that killed at least one person and injured many others. (AP Photo/Francois Mori)
French soldiers patrol in the subway entrance station in Paris, France, Tuesday, March 22, 2016. Authorities are tightening security at airports and on the streets of European cities after attacks on the Brussels airport and subways system that killed at least one person and injured many others. (AP Photo/Francois Mori)
Police officers patrol inside a terminal of the airport during tighter security measures in Barcelona, Spain, Tuesday, March 22, 2016. Explosions, at least one likely caused by a suicide bomber, rocked the Brussels airport and subway system Tuesday, prompting a lockdown of the Belgian capital and heightened security across Europe.(AP Photo/Emilio Morenatti)
Tourist police officers patrol the Red Square in Moscow, Russia, Tuesday, March 22, 2016. Authorities in Europe have tightened security at airports, on subways, at the borders and on city streets after deadly attacks Tuesday on the Brussels airport and its subway system. (AP Photo/ Pavel Golovkin)
Passengers queue at a check in area of the Milan's Malpensa international airport, in Busto Arsizio, Italy, Tuesday, March 22, 2016. Authorities in Europe have tightened security at airports, on subways, at the borders and on city streets after deadly attacks Tuesday on the Brussels airport and its subway system. (AP Photo/Luca Bruno)
PARIS, March 22, 2016-- Police officers patrol at Charles de Gaulle airport in Paris, capital of France, March 22, 2016. Security has been beefed up in France with 1,600 police officers deployed at airports, railway stations and bus stations since the attacks on Brussels Tuesday. (Xinhua/Theo Duval via Getty Images)
BUDAPEST, HUNGARY - MARCH 22: Hungarian counter-terrorism agents secure the Liszt Ferenc International Airport in Budapest, Hungary on March 22, 2016 following high level security alert following the morning explosions in Brussels. At least 34 people were killed and more than 100 injured in multiple explosions at an airport and metro station in Brussels on today's morning. (Photo by Arpad Kurucz/Anadolu Agency/Getty Images)
of
SEE ALL
BACK TO SLIDE
SHOW CAPTION +
HIDE CAPTION

The ready availability of ingredients, compared to military explosives favored by older militant groups like the IRA in Northern Ireland or Basque separatists ETA in Spain, highlights the risks across Europe of more big attacks.

However, the need for premises to manufacture quantities of TATP over several weeks and the final mixture's "use by" date of just a few days make the bombmakers vulnerable to the intensive search efforts of detectives on their trail. French and Belgian police have successfully found and neutralized bomb "factories," most recently in the Paris suburb of Argenteuil on Thursday.

Militants have used fake identities and premises listed with municipal authorities as unoccupied to evade residency checks.

Brussels police failed to find the Schaerbeek flat in time, but were there shortly after the attacks, aided by the taxi driver who unwittingly took the three men to the airport.

Prosecutors uncovered 15 kg (33 lb) of TATP, as well as 180 liters of the chemicals needed to make bombs.

RELATED: Scenes of destruction following the Brussels attacks

78 PHOTOS
Brussels Attacks: Explosions at airport, Maelbeek metro station
See Gallery
Nails and nail varnish: Brussels bombers prepared a 'satanic' cocktail
People are evacuated from Brussels Airport, in Zaventem, on March 22, 2016. after at least 13 people have been killed by two explosions in the departure hall of Brussels Airport. / AFP / Belga / VIRGINIE LEFOUR / Belgium OUT (Photo credit should read VIRGINIE LEFOUR/AFP/Getty Images)
In this image provided by the Belgian Federal Police in Brussels on Tuesday, March 22, 2016 of three men who are suspected of taking part in the attacks at Belgium's Zaventem Airport. The man at right is still being sought by the police and two others in the photo that the police issued were according to a the Belgian Prosecutors 'probably' suicide bombers. Bombs exploded at the Brussels airport and one of the city's metro stations Tuesday, killing and wounding scores of people, as a European capital was again locked down amid heightened security threats. (Belgian Federal Police via AP)
In this image provided by the Belgian Federal Police in Brussels on Tuesday, March 22, 2016, a man who is suspected of taking part in the attacks at Belgium's Zaventem Airport and is being sought by police. Bombs exploded at the Brussels airport and one of the city's metro stations Tuesday, killing and wounding scores of people, as a European capital was again locked down amid heightened security threats. (Belgian Federal Police via AP)
In this undated combination photo provided by the Belgian Federal Police in Brussels on Monday, March 21, 2016, suspect Najim Laachraoui is shown. Belgian prosecutors appealed to the public Monday for information about Laachraoui who allegedly traveled to Hungary in 2015 with the top suspect in the Paris attacks. The federal prosecutor's office said in a statement they are seeking information about 24-year-old Najim Laachraoui, who is said to have traveled to Syria in February 2013. It said Laachraoui was checked by guards at the Austria-Hungary border while driving in a Mercedes with Salah Abdeslam and one other person. (Belgian Federal Police via AP)
#BREAKING: Two loud explosions at #Zaventem airport in #Brussels https://t.co/JFw9RGLjnh
In this still image taken from video from RTL Belgium people receive treatment in the debris strewn terminal at Brussels Airport, in Brussels after explosions Tuesday, March 22, 2016. Authorities locked down the Belgian capital on Tuesday after explosions rocked the Brussels airport and subway system, killing a number of people and injuring many more. Belgium raised its terror alert to its highest level, diverting arriving planes and trains and ordering people to stay where they were. Airports across Europe tightened security. (RTL via AP) BELGIUM OUT TV OUT NO ARCHIVE
In this still image taken from video from RTL Belgium people receive treatment in the debris strewn terminal at Brussels Airport, in Brussels after explosions Tuesday, March 22, 2016. Authorities locked down the Belgian capital on Tuesday after explosions rocked the Brussels airport and subway system, killing a number of people and injuring many more. Belgium raised its terror alert to its highest level, diverting arriving planes and trains and ordering people to stay where they were. Airports across Europe tightened security. (RTL via AP) BELGIUM OUT TV OUT NO ARCHIVE
In this photo provided by Ralph Usbeck an unidentified traveller gets to his feet in a smoke filled terminal at Brussels Airport, in Brussels after explosions Tuesday, March 22, 2016. Authorities locked down the Belgian capital on Tuesday after explosions rocked the Brussels airport and subway system, killing a number of people and injuring many more. Belgium raised its terror alert to its highest level, diverting arriving planes and trains and ordering people to stay where they were. Airports across Europe tightened security. (Ralph Usbeck via AP)
In this photo provided by Ralph Usbeck a police officers directs passengers in a smoke filled terminal at Brussels Airport, in Brussels after explosions Tuesday, March 22, 2016. Authorities locked down the Belgian capital on Tuesday after explosions rocked the Brussels airport and subway system, killing a number of people and injuring many more. Belgium raised its terror alert to its highest level, diverting arriving planes and trains and ordering people to stay where they were. Airports across Europe tightened security. (Ralph Usbeck via AP)
This video footage captures the aftermath of the explosions at Zaventem airport, #Brussels https://t.co/wcsNygh91Y
In this photo provided by Georgian Public Broadcaster and photographed by Ketevan Kardava, armed security personnel are seen in Brussels Airport in Brussels, Belgium, after explosions were heard Tuesday, March 22, 2016. A developing situation left a number dead in explosions that ripped through the departure hall at Brussels airport Tuesday, police said. All flights were canceled, arriving planes were being diverted and Belgium's terror alert level was raised to maximum, officials said. (Ketevan Kardava/ Georgian Public Broadcaster via AP)
In this photo provided by Georgian Public Broadcaster and photographed by Ketevan Kardava two women wounded in Brussels Airport in Brussels, Belgium, after explosions were heard Tuesday, March 22, 2016. A developing situation left at least one person and possibly more dead in explosions that ripped through the departure hall at Brussels airport Tuesday, police said. All flights were canceled, arriving planes were being diverted and Belgium's terror alert level was raised to maximum, officials said. (Ketevan Kardava/ Georgian Public Broadcaster via AP)
In this photo provided by Georgian Public Broadcaster and photographed by Ketevan Kardava a man is wounded in Brussels Airport in Brussels, Belgium, after explosions were heard Tuesday, March 22, 2016. A developing situation left at least one person and possibly more dead in explosions that ripped through the departure hall at Brussels airport Tuesday, police said. All flights were canceled, arriving planes were being diverted and Belgium's terror alert level was raised to maximum, officials said. (Ketevan Kardava/ Georgian Public Broadcaster via AP)
This photo provided by Georgian Public Broadcaster and photographed by Ketevan Kardava, shows the scene in Brussels Airport in Brussels, Belgium, after explosions were heard Tuesday, March 22, 2016. A developing situation left a number dead in explosions that ripped through the departure hall at Brussels airport Tuesday, police said. All flights were canceled, arriving planes were being diverted and Belgium's terror alert level was raised to maximum, officials said. (Ketevan Kardava/ Georgian Public Broadcaster via AP)
In this photo provided by Ralph Usbeck an unidentified traveller gets to his feet in a smoke filled terminal at Brussels Airport, in Brussels after explosions Tuesday, March 22, 2016. Authorities locked down the Belgian capital on Tuesday after explosions rocked the Brussels airport and subway system, killing a number of people and injuring many more. Belgium raised its terror alert to its highest level, diverting arriving planes and trains and ordering people to stay where they were. Airports across Europe tightened security. (Ralph Usbeck via AP)
In this photo provided by Georgian Public Broadcaster and photographed by Ketevan Kardava a man is wounded in Brussels Airport in Brussels, Belgium, after explosions were heard Tuesday, March 22, 2016. A developing situation left at least one person and possibly more dead in explosions that ripped through the departure hall at Brussels airport Tuesday, police said. All flights were canceled, arriving planes were being diverted and Belgium's terror alert level was raised to maximum, officials said. (Ketevan Kardava/ Georgian Public Broadcaster via AP)
In this photo provided by Georgian Public Broadcaster and photographed by Ketevan Kardava, an injured man lies on the floor in Brussels Airport in Brussels, Belgium, after explosions were heard Tuesday, March 22, 2016. A developing situation left a number dead in explosions that ripped through the departure hall at Brussels airport Tuesday, police said. All flights were canceled, arriving planes were being diverted and Belgium's terror alert level was raised to maximum, officials said. (Ketevan Kardava/ Georgian Public Broadcaster via AP)
In this photo provided by Georgian Public Broadcaster and photographed by Ketevan Kardava a man is wounded in Brussels Airport in Brussels, Belgium, after explosions were heard Tuesday, March 22, 2016. A developing situation left a number dead in explosions that ripped through the departure hall at Brussels airport Tuesday, police said. All flights were canceled, arriving planes were being diverted and Belgium's terror alert level was raised to maximum, officials said. (Ketevan Kardava/ Georgian Public Broadcaster via AP)
In this photo provided by Ralph Usbeck travellers stand in a smoke filled terminal at Brussels Airport, in Brussels after explosions Tuesday, March 22, 2016. Authorities locked down the Belgian capital on Tuesday after explosions rocked the Brussels airport and subway system, killing a number of people and injuring many more. Belgium raised its terror alert to its highest level, diverting arriving planes and trains and ordering people to stay where they were. Airports across Europe tightened security. (Ralph Usbeck via AP)
Brussels aftermath video shows survivors huddled together, telling one another: "It's okay". https://t.co/3Y7lEXrrjP https://t.co/KdqFXR9Wft
BRUSSELS, BELGIUM - MARCH 22: Passengers are evacuated from Zaventem Bruxelles International Airport after a terrorist attack on March 22, 2016 in Brussels, Belgium. At least 13 people are though to have been killed after Brussels airport was hit by two explosions whilst a Metro station was also targeted. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Sylvain Lefevre/Getty Images)
The blown out windows of Zaventem airport are seen after a deadly attack in Brussels, Belgium, Tuesday, March 22, 2016. Authorities in Europe have tightened security at airports, on subways, at the borders and on city streets after deadly attacks Tuesday on the Brussels airport and its subway system. (AP Photo/Peter Dejong)
A private security guard helps a wounded women outside the Maalbeek metro station in Brussels on March 21, 2016 after a blast at this station located near the EU institutions. Belgian firefighters said at least 26 people had died after 'enormous' blasts rocked Brussels airport and a city metro station today, as Belgium raised its terror threat to the maximum level. / AFP / Michael VILLA (Photo credit should read MICHAEL VILLA/AFP/Getty Images)
People react as they walk away from Brussels airport after explosions rocked the facility in Brussels, Belgium Tuesday March 22, 2016. Explosions rocked the Brussels airport and the subway system Tuesday, just days after the main suspect in the November Paris attacks was arrested in the city, police said. (AP Photo/Geert Vanden Wijngaert)
In this photo provided by David Crunelle, an injured woman leaves the scene at Brussels airport, after explosions rocked the facility in Brussels, Belgium, Tuesday March 22, 2016. Authorities locked down the Belgian capital on Tuesday after explosions rocked the Brussels airport and subway system, killing at least 13 people and injuring many more. Belgium raised its terror alert to its highest level, diverting arriving planes and trains and ordering people to stay where they were. Airports across Europe tightened security. (David Crunelle via AP) NO SALES - NO ARCHIVES
A picture taken on March 22, 2016 shows a Belgian police vehicle driving past passengers who are evacuating the Brussels Airport of Zaventem. At least 13 people were killed and 35 injured as twin blasts rocked the main terminal of Brussels airport on March 22, 2016, Belgian media quoted the federal prosecutor as saying. Officials were not immediately available to confirm the figure when contacted by AFP. The federal police earlier confirmed one death. / AFP / Belga / Jonas Roosens / Belgium OUT (Photo credit should read JONAS ROOSENS/AFP/Getty Images)
People react as they walk away from Brussels airport after explosions rocked the facility in Brussels, Belgium Tuesday March 22, 2016. Explosions rocked the Brussels airport and the subway system Tuesday, just days after the main suspect in the November Paris attacks was arrested in the city, police said. (AP Photo/Geert Vanden Wijngaert)
People react outside Brussels airport after explosions rocked the facility in Brussels, Belgium Tuesday March 22, 2016. Explosions rocked the Brussels airport and the subway system Tuesday, just days after the main suspect in the November Paris attacks was arrested in the city, police said. (AP Photo/Geert Vanden Wijngaert)
People react as they walk away from Brussels airport after explosions rocked the facility in Brussels, Belgium Tuesday March 22, 2016. Explosions rocked the Brussels airport and the subway system Tuesday, just days after the main suspect in the November Paris attacks was arrested in the city, police said. (AP Photo/Geert Vanden Wijngaert)
A picture taken on March 22, 2016 shows a Belgian police vehicle driving past passengers who are evacuating the Brussels Airport of Zaventem. At least 13 people were killed and 35 injured as twin blasts rocked the main terminal of Brussels airport on March 22, 2016, Belgian media quoted the federal prosecutor as saying. Officials were not immediately available to confirm the figure when contacted by AFP. The federal police earlier confirmed one death. / AFP / Belga / Jonas Roosens / Belgium OUT (Photo credit should read JONAS ROOSENS/AFP/Getty Images)
In this image taken from TV people receive treatment as emergency services attend the scene after an explosion in a main metro station in Brussels on Tuesday, March 22, 2016. Explosions rocked the Brussels airport and the subway system Tuesday, killing at least 13 people and injuring many others just days after the main suspect in the November Paris attacks was arrested in the city, police said. (AP Photo)
In this image taken from TV an armed member of the security forces stands guard as emergency services attend the scene after a explosion in a main metro station in Brussels on Tuesday, March 22, 2016. Explosions rocked the Brussels airport and the subway system Tuesday, killing a number of people and injuring many others just days after the main suspect in the November Paris attacks was arrested in the city, police said. (AP Photo)
In this image made from video, emergency rescue workers stretcher an unidentified person at the site of an explosion at a metro station in Brussels, Belgium, March 22, 2016. Explosions rocked the Brussels airport and the subway system Tuesday, just days after the main suspect in the November Paris attacks was arrested in the city, police said.(APTN via AP)
A picture taken on March 22, 2016 shows smoke rising from the Maalbeek underground, in Brussels, following a blast at the station close to the capital's European quarter. The Brussels metro service was being shut down on March 22, its operator said. The measure came after a rush-hour explosion at Maalbeek station with TV images showing black smoke pouring from the station entrance. / AFP / Belga / Seppe KNAPEN / Belgium OUT (Photo credit should read SEPPE KNAPEN/AFP/Getty Images)
A security perimeter has been set, on March 22, 2016 near Maalbeek metro station in Brussels, after a blast at this station near the EU institutions caused deaths and injuries. AFP PHOTO / EMMANUEL DUNAND / AFP / EMMANUEL DUNAND (Photo credit should read EMMANUEL DUNAND/AFP/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: Broken glass and blood is seen beside signage outside an entrance to Maelbeek metro station following todays attack on March 22, 2016 in Brussels, Belgium. At least 34 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Carl Court/Getty Images)
BRUSSELS, BELGIUM - MARCH 22: Broken glass is seen outside an entrance to Maelbeek metro station following todays attack on March 22, 2016 in Brussels, Belgium. At least 34 people are thought to have been killed after Brussels airport and a Metro station were targeted by explosions. The attacks come just days after a key suspect in the Paris attacks, Salah Abdeslam, was captured in Brussels. (Photo by Carl Court/Getty Images)
Policemen stand guard at the entrance of a security perimeter set near Maalbeek metro station, on March 22, 2016 in Brussels, after a blast at this station near the EU institutions caused deaths and injuries. AFP PHOTO / EMMANUEL DUNAND / AFP / EMMANUEL DUNAND (Photo credit should read EMMANUEL DUNAND/AFP/Getty Images)
Rescue teams evacuate wounded people outside the Maalbeek metro station in Brussels on March 22, 2016 after a blast at this station located near the EU institutions. Belgian firefighters said at least 26 people had died after 'enormous' blasts rocked Brussels airport and a city metro station today, as Belgium raised its terror threat to the maximum level. / AFP / - (Photo credit should read -/AFP/Getty Images)
Passengers evacuated after blast at #Maalbeek metro station in #Brussels via @EurActiv https://t.co/O3W8C2rpPm https://t.co/XmIoeKfE9F
In this photo provided by Evan Lamos passengers clamber from a metro carriage after explosions in Brussels Tuesday, March 22, 2016. Authorities locked down the Belgian capital on Tuesday after explosions rocked the Brussels airport and subway system, killing a number of people and injuring many more. Belgium raised its terror alert to its highest level, diverting arriving planes and trains and ordering people to stay where they were. Airports across Europe tightened security. (Evan Lamos via AP)
In this photo provided by Evan Lamos passengers walk inside the metro system after explosions in Brussels Tuesday, March 22, 2016. Authorities locked down the Belgian capital on Tuesday after explosions rocked the Brussels airport and subway system, killing a number of people and injuring many more. Belgium raised its terror alert to its highest level, diverting arriving planes and trains and ordering people to stay where they were. Airports across Europe tightened security. (Evan Lamos via AP)
In this image provided by Daniela Schwarzer, smoke is seen at Brussels airport in Brussels, Belgium, after explosions were heard Tuesday, March 22, 2016. (Daniela Schwarzer via AP)
Smoke billows from the Zaventem Airport after a controlled explosion in Brussels, Tuesday, March 22, 2016. Bombs struck the Brussels airport and one of the city's metro stations Tuesday, killing and wounding dozens of people, as a European capital was again locked down amid heightened security threats. (AP Photo/Michel Spingler)
People are evacuated from Brussels airport in Zaventem on March 22, 2016 following twin blasts. A string of explosions rocked Brussels airport and a city metro station, killing at least 21 people in apparently coordinated attacks, officials said. == BELGIUM OUT == / AFP / Belga / DIRK WAEM / Belgium OUT (Photo credit should read DIRK WAEM/AFP/Getty Images)
A man with blood stains on his sweater leaves Brussels airport in Zaventem on March 22, 2016 following twin blasts. A string of explosions rocked Brussels airport and a city metro station, killing at least 21 people in apparently coordinated attacks, officials said. == BELGIUM OUT == / AFP / Belga / DIRK WAEM / Belgium OUT (Photo credit should read DIRK WAEM/AFP/Getty Images)
Amateur footage shows scene at #Brussels airport after explosions (video: Bart van Meele) https://t.co/v29k9dvMiM
People stand near Brussels airport after being evacuated following explosions that rocked the facility in Brussels, Belgium, Tuesday March 22, 2016. Authorities locked down the Belgian capital on Tuesday after explosions rocked the Brussels airport and subway system, killing a number of people and injuring many more. Belgium raised its terror alert to its highest level, diverting arriving planes and trains and ordering people to stay where they were. Airports across Europe tightened security. (AP Photo/Geert Vanden Wijngaert)
Passengers are evacuated from Brussels airport, on March 22, 2016 in Zaventem, after at least 13 people were killed and 35 injured as twin blasts rocked the main terminal of Brussels airport.AFP PHOTO / JOHN THYS / AFP / JOHN THYS (Photo credit should read JOHN THYS/AFP/Getty Images)
A victim is evacuated on a stretcher by emergency services after a explosion in a main metro station in Brussels on Tuesday, March 22, 2016. Explosions rocked the Brussels airport and the subway system Tuesday, killing at least 13 people and injuring many others just days after the main suspect in the November Paris attacks was arrested in the city, police said. (AP Photo/Virginia Mayo)
People comfort each other after being evacuated from Brussels airport, after explosions rocked the facility in Brussels, Belgium, Tuesday March 22, 2016. Authorities locked down the Belgian capital on Tuesday after explosions rocked the Brussels airport and subway system, killing at least 13 people and injuring many more. Belgium raised its terror alert to its highest level, diverting arriving planes and trains and ordering people to stay where they were. Airports across Europe tightened security. (AP Photo/Geert Vanden Wijngaert)
A victim receives first aid by rescuers, on March 22, 2016 near Maalbeek metro station in Brussels, after a blast at this station near the EU institutions caused deaths and injuries. AFP PHOTO / EMMANUEL DUNAND / AFP / EMMANUEL DUNAND (Photo credit should read EMMANUEL DUNAND/AFP/Getty Images)
A woman is evacuated in an ambulance by emergency services after a explosion in a main metro station in Brussels on Tuesday, March 22, 2016. Explosions rocked the Brussels airport and the subway system Tuesday, killing at least 13 people and injuring many others just days after the main suspect in the November Paris attacks was arrested in the city, police said. (AP Photo/Virginia Mayo)
In this image taken from TV an injured person is evacuated as emergency services attend the scene after an explosion in a main metro station in Brussels on Tuesday, March 22, 2016. Explosions rocked the Brussels airport and the subway system Tuesday, killing a number of people and injuring many others just days after the main suspect in the November Paris attacks was arrested in the city, police said. (AP Photo)
A woman is evacuated by emergency services after a explosion in a main metro station in Brussels on Tuesday, March 22, 2016. Explosions rocked the Brussels airport and the subway system Tuesday, killing at least 13 people and injuring many others just days after the main suspect in the November Paris attacks was arrested in the city, police said. (AP Photo/Virginia Mayo)
People react outside Brussels airport after explosions rocked the facility in Brussels, Belgium Tuesday March 22, 2016. Explosions rocked the Brussels airport and the subway system Tuesday, just days after the main suspect in the November Paris attacks was arrested in the city, police said. (AP Photo/Geert Vanden Wijngaert)
A victim receives first aid by rescuers, on March 22, 2016 near Maalbeek metro station in Brussels, after a blast at this station near the EU institutions caused deaths and injuries. AFP PHOTO / EMMANUEL DUNAND / AFP / EMMANUEL DUNAND (Photo credit should read EMMANUEL DUNAND/AFP/Getty Images)
A truck carrying soldiers of the Belgian Army arrives after a explosion in a main metro station in Brussels on Tuesday, March 22, 2016. Explosions rocked the Brussels airport and the subway system Tuesday, killing at least 13 people and injuring many others just days after the main suspect in the November Paris attacks was arrested in the city, police said. (AP Photo/Virginia Mayo)
BRUSSELS, BELGIUM - MARCH 22 : Police officers stand guard around the Zaventem Airport after two explosions went off in Brussels, Belgium on March 22, 2016. (Photo by Dursun Aydemir/Anadolu Agency/Getty Images)
BRUSSELS, BELGIUM - MARCH 22 : Police officers stand guard around the Zaventem Airport after two explosions went off in Brussels, Belgium on March 22, 2016. (Photo by Dursun Aydemir/Anadolu Agency/Getty Images)
A young girl looks out of the window of a bus after being evacuated from Brussels airport, after explosions rocked the facility in Brussels, Belgium, Tuesday March 22, 2016. Authorities locked down the Belgian capital on Tuesday after explosions rocked the Brussels airport and subway system, killing at least 13 people and injuring many more. Belgium raised its terror alert to its highest level, diverting arriving planes and trains and ordering people to stay where they were. Airports across Europe tightened security. (AP Photo/Geert Vanden Wijngaert)
Passengers leave a gym where they took shelter after the explosions, near the Zaventem Airport in Brussels, Tuesday, March 22, 2016. Bombs struck the Brussels airport and one of the city's metro stations Tuesday, killing and wounding dozens of people, as a European capital was again locked down amid heightened security threats. (AP Photo/Michel Spingler)
Passengers are gathered, on March 22, 2016 near Brussels airport in Zaventem, following its evacuation after at least 13 people were killed and 35 injured as twin blasts rocked the main terminal of Brussels airport.AFP PHOTO / JOHN THYS / AFP / JOHN THYS (Photo credit should read JOHN THYS/AFP/Getty Images)
People react as they walk away from Brussels airport after explosions rocked the facility in Brussels, Belgium Tuesday March 22, 2016. Explosions rocked the Brussels airport and the subway system Tuesday, just days after the main suspect in the November Paris attacks was arrested in the city, police said. (AP Photo/Geert Vanden Wijngaert)
In this photo provided by David Crunelle, injured people leave the scene at Brussels airport, after explosions rocked the facility in Brussels, Belgium, Tuesday March 22, 2016. Authorities locked down the Belgian capital on Tuesday after explosions rocked the Brussels airport and subway system, killing a number of people and injuring many more. Belgium raised its terror alert to its highest level, diverting arriving planes and trains and ordering people to stay where they were. Airports across Europe tightened security. (David Crunelle via AP) NO SALES - NO ARCHIVES
BRUSSELS, BELGIUM - MARCH 22 : Police officers stand guard around the Zaventem Airport after two explosions went off in Brussels, Belgium on March 22, 2016. (Photo by Dursun Aydemir/Anadolu Agency/Getty Images)
Firefighters arrive at a security perimeter set in the Rue de la Loi near the Maalbeek subway station, in Brussels, on March 22, 2016, after an explosion killed around 10 people, according to spokesman of Brussels' fire brigade A string of explosions rocked Brussels airport and a city metro station on Tuesday, killing at least 13 people, according to media reports, as Belgium raised its terror threat to the maximum level. / AFP / Belga / LAURIE DIEFFEMBACQ / Belgium OUT (Photo credit should read LAURIE DIEFFEMBACQ/AFP/Getty Images)
Passengers who were evacuated from the airport wait in Zaventem, on March 22, 2016, after a string of explosions rocked Brussels airport of Zaventem and a city metro station, killing at least 13 people, according to media reports, as Belgium raised its terror threat to the maximum level. / AFP / Belga / SEPPE KNAPEN / Belgium OUT (Photo credit should read SEPPE KNAPEN/AFP/Getty Images)
BRUSSELS, BELGIUM - MARCH 22 : Police officers stand guard around the Zaventem Airport after two explosions went off in Brussels, Belgium on March 22, 2016. (Photo by Dursun Aydemir/Anadolu Agency/Getty Images)
People react outside Brussels airport after explosions rocked the facility in Brussels, Belgium Tuesday March 22, 2016. Explosions rocked the Brussels airport and the subway system Tuesday, just days after the main suspect in the November Paris attacks was arrested in the city, police said. (AP Photo/Geert Vanden Wijngaert)
People are evacuated from Brussels Airport, in Zaventem, on March 22, 2016. after at least 13 people have been killed by two explosions in the departure hall of Brussels Airport. / AFP / Belga / VIRGINIE LEFOUR / Belgium OUT (Photo credit should read VIRGINIE LEFOUR/AFP/Getty Images)
People stand near Brussels airport after being evacuated following explosions that rocked the facility in Brussels, Belgium, Tuesday March 22, 2016. Authorities locked down the Belgian capital on Tuesday after explosions rocked the Brussels airport and subway system, killing a number of people and injuring many more. Belgium raised its terror alert to its highest level, diverting arriving planes and trains and ordering people to stay where they were. Airports across Europe tightened security. (AP Photo/Geert Vanden Wijngaert)
Passengers gather, on March 22, 2016 near Brussels airport in Zaventem , following its evacuation after at least 13 people were killed and 35 injured as twin blasts rocked the main terminal of Brussels airport.AFP PHOTO / JOHN THYS / AFP / JOHN THYS (Photo credit should read JOHN THYS/AFP/Getty Images)
Passengers leave with their luggages, on March 22, 2016 near Brussels airport in Zaventem , following its evacuation after at least 13 people were killed and 35 injured as twin blasts rocked the main terminal of Brussels airport.AFP PHOTO / JOHN THYS / AFP / JOHN THYS (Photo credit should read JOHN THYS/AFP/Getty Images)
BRUSSELS, BELGIUM - MARCH 22 : Police officers stand guard around the Zaventem Airport after two explosions went off in Brussels, Belgium on March 22, 2016. (Photo by Dursun Aydemir/Anadolu Agency/Getty Images)
A photo taken on March 22, 2016 shows Brussels Airport, in Zaventem, after two explosions rocked the main hall of the airport. At least 13 people have been killed after two explosions occured in the departure hall of Brussels Airport. Government sources speak of a terrorist attack. The terrorist threat level has been heightened to four across the country. / AFP / BELGA / DIRK WAEM / Belgium OUT (Photo credit should read DIRK WAEM/AFP/Getty Images)
of
SEE ALL
BACK TO SLIDE
SHOW CAPTION +
HIDE CAPTION

"MOTHER OF SATAN"

TATP is a highly volatile explosive. Palestinian insurgents who experimented with it in the 1980s nicknamed it "the mother of Satan" because the white crystal powder can be easily detonated by a cigarette, a match or too much heat.

It also loses its potency over time as the chemicals decay.

Used in the 2005 London bombings and the Nov. 13 Paris attacks, and found in a series of foiled bomb attempts in Europe since 2007, TATP appears to be Islamic State's explosive of choice.

However, unlike the smuggled firearms also used in the Paris attacks that killed 130 people, TATP offers no easy trail for European intelligence agents to track because purchasing the ingredients is easily done at any local hardware store or pharmacy and rarely attracts attention.

Making a TATP bomb, although a more lengthy process than the fertilizer-based explosives used by other European militants, is cheap and simple and recipes and videos by chemistry buffs abound on the Internet. It was discovered by a 19th century German chemist and is very powerful, even in small quantities.

All the ingredients - acetone found in cleaning products, hydrogen peroxide found in wood bleach and sulphuric acid used to unblock kitchen pipes - were available at one Brussels hardware store this week for less than 40 euros ($45).

Nails and bolts can be added to increase the bomb's impact and afterwards stuffed into bags and taped into suicide belts.

It goes undetected by airport scanners, leaving authorities to rely on sniffer dogs. Though the bombs can have a strong smell -- the bombers' taxi driver said he smelled chemicals on the ride to the airport -- there were few such dogs in the Brussels' airport check-in area on Tuesday when the men detonated the explosives hidden in holdalls on baggage trolleys, according to several witnesses, including an airport worker.

Aftermath of Attack on Brussels Airport

CHEMISTRY STUDENT

Ehud Keinan, an Israeli scientist who has spent 35 years studying TATP, said that as little as 4 kg could produce the kind of devastation seen in Brussels.

"It is very easy to make, not like a conventional bomb," said Keinan, the dean of chemistry at Technion-Israel Institute of Technology in Haifa. "You don't need to be part of a large organization or need training to do this."

Still, one of the three Brussels suspects, Najim Laachraoui, a 25-year-old Belgian who blew himself up in the airport attack and is suspected of making suicide vests for Paris, had studied engineering at university and excelled in lab work.

Islamic State is also making TATP on an industrial scale in Syria and Iraq, according to a report last month by EU-funded Conflict Armament Research.

The emergence of Kalashnikov assault rifles as a weapon of choice for Islamic State in Europe in the past two years, notably in Paris, has led to EU efforts to crack down on weapons traffickers.

But disrupting TATP supplies is harder.

The European Union in 2014 passed new legislation for all the bloc's 28 countries to restrict the marketing and use of chemicals that could be used to make explosives, and in some cases requires identity checks on those purchasing them.

Within two weeks of the July 2005 London attacks, the British chemical industry and British hardware stores stepped up their reporting of suspicious or large purchases of chemicals.

However, in France, the explosive precursor hydrogen peroxide is sold legally as a way to clean private swimming pool water and no one is considering banning nail varnish remover.

"If you go into any pharmacy in Brussels, you can buy 50 ml of acetone. If you go into a hundred pharmacies, you can get that much more," said Peter Newport, the chief executive of Britain's Chemical Business Association, which sits on the European Commission's expert group on regulating precursors.

"There are so many valid uses by the public of these substances."

($1 = 0.8964 euros)

Read Full Story

Sign up for Breaking News by AOL to get the latest breaking news alerts and updates delivered straight to your inbox.

Subscribe to our other newsletters

Emails may offer personalized content or ads. Learn more. You may unsubscribe any time.

From Our Partners