New York-Based Siblings killed in Brussels were 'sweet and wonderful'

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Brussels Attacks: 2 Americans Confirmed Killed

Sascha and Alexander Pinczowski were world travelers who friends described as kind-hearted and quick to make those around them laugh.

The siblings, who died in the Brussels terror attacks, were Dutch nationals who lived in New York. They intended to become U.S. citizens, according to Jim Cain, the former U.S. ambassador to Denmark, whose daughter, Cameron, was dating Alexander.

Cameron and Alexander planned on getting married, Cain told NBC News, and both Alexander and his sister wanted to get American citizenship — "Alex, of course, after he married our daughter."

See photos of the siblings:

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Americans Sascha, Alexander Pinczowski killed in Brussels blasts
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New York-Based Siblings killed in Brussels were 'sweet and wonderful'

Alexander and Sascha Pinczowski

(Photo via Facebook)

Alexander Pinczowski

(Photo via Facebook)

Sascha Pinczowski

(Photo via Facebook)
New York City Siblings Alexander and Sascha Pinczowski Killed in Brussels Terror Attack https://t.co/Ay2ZqxMvXl https://t.co/kbBQtkMh5P
R.I.P. Sascha Pinczowski: “The kindest, goofiest, and down-to-earth girl I have ever met.” https://t.co/9vsvNXtj0W https://t.co/7aD83IYomT
If you have info on Sascha & Alexander Pinczowski, get in touch, my friends haven't heard from them yet. 😔 #Brussels https://t.co/Mw9kbqaGlu
Americans Sascha and Alexander Pinczowski missing after #BrusselsAttacks https://t.co/38KjBEVc2H https://t.co/u2k3aiKth2
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The brother and sister had come to Brussels via the Netherlands, where they had been visiting family, according to CBS New York. Other news outlets, including Dutch newspaper Algemeen Dagblad, reported their father is from Maastricht, a town in the Netherlands.

Related: New York-Based Sascha, Alexander Pinczowski Killed in Brussels Blasts

They had just arrived at the Brussels airport to fly back to New York and were on the phone with a relative when two explosions went off in quick succession. A third blast later went off in a metro station.

ISIS has claimed responsibility for the attacks, which killed at least 31 and injured more than 270.

Tributes and memorials around the world after the Brussels attacks:

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World reacts to Brussels attacks -- tributes, memorials
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New York-Based Siblings killed in Brussels were 'sweet and wonderful'
TOPSHOT - A Belgian flag is display on the Trevi Fountain in Rome on March 22, 2016 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 / GABRIEL BOUYS (Photo credit should read GABRIEL BOUYS/AFP/Getty Images)
The Eiffel Tower is illuminated with the Belgium national colors black, yellow and red in honor of the victims of the today's attacks at the airport and the metro station in Brussels, in Paris, Tuesday, March 22, 2016. Explosions, at least one likely caused by a suicide bomber, rocked the Brussels airport and its subway system Tuesday, prompting a lockdown of the Belgian capital and heightened security across Europe. (AP Photo/Thibault Camus)
The full moon rises behind One World Trade Center on March 22, 2016 in New York, it's mast displaying the colors of the Belgian flag in a show of support following the terrorist attacks in Brussels. / AFP / TREVOR COLLENS (Photo credit should read TREVOR COLLENS/AFP/Getty Images)
A picture taken on March 22, 2016 shows the Belgian flag projected on the European Union Commission building 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 / PHILIPPE HUGUEN (Photo credit should read PHILIPPE HUGUEN/AFP/Getty Images)
A picture taken on March 22, 2016, shows the town council building in Belgrade illuminated in the colours of the Belgian flag in tribute to the victims of Brussels following attacks in the Belgian capital that killed about 35 people and left more than 200 people wounded. / AFP / Oksana Toskic / Serbia OUT (Photo credit should read OKSANA TOSKIC/AFP/Getty Images)
PARIS, FRANCE - MARCH 22: French people gather in front of the Hotel de Ville to show solidarity with Belgians during a commemoration, held with the attendance of French Minister of Foreign Affairs Jean Marc Ayrault, Belgium Ambassador to Paris Vincent Mertens de Wilmars and Mayor of Paris, Anne Hidalgo in Paris, France on March 22, 2016. At least 34 people were killed and more than 100 injured in multiple terrorist attacks at an airport and metro station in Brussels on today's morning. (Photo by Geoffroy Van der Hasselt/Anadolu Agency/Getty Images)
(COMBO) This combination of pictures created on March 22, 2016 shows colours of the Belgian flag being projected on to (from top L) the Brandenburg Gate in Berlin, the Eiffel Tower in Paris, the town council building in Belgrade, the Trevi Fountain in Rome, the Royal Palace at Dam Square in Amsterdam and Rome's Campidoglio in tribute to the victims of Brussels following the triple bomb attacks that killed about 35 people and left more than 200 people wounded. / AFP / AFP AND ANP / Serbia OUT - Netherlands OUT (Photo credit should read ODD ANDERSEN,LIONEL BONAVENTURE,OKSANA TOSKIC,GABRIEL BOUYS,EVERT ELZINGA,FILIPPO MONTEFORTE/AFP/Getty Images)
TOPSHOT - A couple embraces as the colors of the Belgian flag are projected on to the Brandenburg Gate in Berlin as the German capital shows its solidarity following the Brussels attacks on March 22, 2016. Security was tightened across Europe and transport links paralysed after a series of apparently coordinated explosions ripped through Brussels airport and a metro train, killing at least 34 people. / AFP / ODD ANDERSEN (Photo credit should read ODD ANDERSEN/AFP/Getty Images)
A picture taken on March 22, 2016 shows the Eiffel Tower in Paris illuminated in colours of the Belgian flag in tribute to the victims of terrorist attacks in Brussels. Around 35 people were killed and more than 200 wounded in a series of attacks in Brussels today claimed by the Islamic State group and described as a strike at the very heart of Europe. AFP PHOTO / LIONEL BONAVENTURE / AFP / LIONEL BONAVENTURE (Photo credit should read LIONEL BONAVENTURE/AFP/Getty Images)
PARIS, FRANCE - MARCH 22: (FRANCE OUT) Flags are hung on the Hotel de Ville to pay tribute to the victims of the terrorists attacks in Belgium on March 22, 2016 in Paris, France. 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 Nicolas Kovarik/IP3/Getty Images)
LONDON, ENGLAND - MARCH 22: The Belgian national flag is raised as a mark of respect at Downing Street on March 22, 2016 in London, England. 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 Ben Pruchnie/Getty Images)
TORONTO, ON- MARCH 22: Magali Labe from Belgium holds for a moment of silence at a vigil. The Toronto Sign outside City Hall sports black-yellow-red of Belgium in symapathy of those killed and injured in Brussels earlier in the day. at City Hall in Toronto. March 22, 2016. (Steve Russell/Toronto Star via Getty Images)
TORONTO, ON- MARCH 22: The Toronto Sign outside City Hall sports black-yellow-red of Belgium in symapathy of those killed and injured in Brussels earlier in the day. at City Hall in Toronto. March 22, 2016. (Steve Russell/Toronto Star via Getty Images)
ISTANBUL, TURKEY - MARCH 22: Belgian Consul to Istanbul Henri Marc Jose Vantieghem, US Consul to Istanbul Charles Frederick Hunter, Israel's Consul to Istanbul Shai Cohen, Mayors of Istanbul's Districts Beyoglu, Fatih, Esenler and Turkey's ruling party Justice and Development Party's (AK Party) Provincial members walks during a protest, condemning terrorism on March 22, 2016 in Istanbul, Turkey. Four people were killed and 36 injured, 7 of them seriously, in Saturdays suicide bomb blast on Istanbuls Istiklal Street. Also, 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. Metro stations were closed and flights to Zaventem airport diverted while the Eurostar rail service was also cancelled into and out of Brussels. (Photo by Islam Yakut/Anadolu Agency/Getty Images)
PARIS, FRANCE - MARCH 22: French people leave flowers to pay respect to Belgium after Brussels Terror attack, at the Belgian Embassy in Paris, France on March 22, 2016. (Photo by Geoffroy Van der Hasselt/Anadolu Agency/Getty Images)
PARIS, FRANCE - MARCH 22: French people leave French flag and flowers to pay respect to Belgium after Brussels Terror attack, at the Belgian Embassy in Paris, France on March 22, 2016. (Photo by Geoffroy Van der Hasselt/Anadolu Agency/Getty Images)
PARIS, FRANCE - MARCH 22: French people leave flowers to pay respect to Belgium after Brussels Terror attack, at the Belgian Embassy in Paris, France on March 22, 2016. (Photo by Geoffroy Van der Hasselt/Anadolu Agency/Getty Images)
UNITED STATES - MARCH 22 - Flowers are let below the Belgium flag as it flies at half staff at the Belgium Embassy in Washington D.C., Tuesday, March 22, 2016, after the terror attacks in Brussels, Belgium, earlier today. (Photo By Al Drago/CQ Roll Call)
UNITED STATES - MARCH 22 - Flowers are let below the Belgium flag as it flies at half staff at the Belgium Embassy in Washington D.C., Tuesday, March 22, 2016, after the terror attacks in Brussels, Belgium, earlier today. (Photo By Al Drago/CQ Roll Call)
Flowers wrapped in ribbons in the colours of the Belgium national flag, are placed outside the Belgium Embassy in Moscow, Russia on 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)
Activists of Pakistani civil society chant slogans during a rally to condemn the Brussels attack, in Multan, Pakistan, Tuesday, March 22, 2016. Explosions, at least one likely caused by a suicide bomber, rocked the Brussels airport and subway system Tuesday, prompting a lock down of the Belgian capital and heightened security across Europe. Placard at left reads, "we want peace in the world." (AP Photo/Asim Tanveer)
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)
A picture taken on March 22, 2016 in Paris shows a view of a smartphone screening an Instagram page with the ashtag '#JESUISBRUSSELS' (#IAMBRUSSELS) and two tributes images picturing the color of the Belgian flag, a drawing by French cartoonist Plantu and the famous Belgian comic character Tintin, in tribute to victims of triple bomb attacks in the Belgian capital that killed about 35 people. Airlines cancelled hundreds of flights and European railways froze links with Brussels on March 22, 2016 after rush-hour bomb attacks killed around 35 people in the city's airport and a metro train, sparking a broad security response. Within hours of Brussels attacks tens of thousands of people were sharing images on social media of Herge's cub reporter Tintin, the country's most famous creation, in tears. / AFP / JOEL SAGET / RESTRICTED TO EDITORIAL USE - MANDATORY MENTION OF THE ARTIST UPON PUBLICATION - TO ILLUSTRATE THE EVENT AS SPECIFIED IN THE CAPTION (Photo credit should read JOEL SAGET/AFP/Getty Images)
A picture taken on March 22, 2016 in Paris shows a view of a smartphone screening an Instagram page with the ashtag '#JESUISBRUSSELS' (#IAMBRUSSELS) and various tributes images picturing the Belgian flag, a drawing by French cartoonist Plantu or the famous Belgian comic character Tintin in tribute to victims of triple bomb attacks in the Belgian capital that killed about 35 people. Airlines cancelled hundreds of flights and European railways froze links with Brussels on March 22, 2016 after rush-hour bomb attacks killed around 35 people in the city's airport and a metro train, sparking a broad security response. Within hours of Brussels attacks tens of thousands of people were sharing images on social media of Herge's cub reporter Tintin, the country's most famous creation, in tears. / AFP / JOEL SAGET / RESTRICTED TO EDITORIAL USE - MANDATORY MENTION OF THE ARTIST UPON PUBLICATION - TO ILLUSTRATE THE EVENT AS SPECIFIED IN THE CAPTION (Photo credit should read JOEL SAGET/AFP/Getty Images)
Tributes to the victims of the terror attacks in Brussels are seen inside the Belgian Embassy in central London on March 22, 2016. Security was tightened across Europe and transport links paralysed after a series of apparently coordinated explosions ripped through Brussels airport and a metro train, killing at least 35 people. / AFP / JUSTIN TALLIS (Photo credit should read JUSTIN TALLIS/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)
MOSCOW, RUSSIA.MARCH 22, 2016. People bring flowers to the Belgian Embassy in Moscow to pay tribute to the Brussels terror attacks victims. On March 22, 2016, two explosions rocked Zaventem Airport and one blast struck a metro station. Mikhail Japaridze/TASS (Photo by Mikhail Japaridze\TASS via Getty Images)
A boy holds a placard expressing sympathy for the victims of the terror attacks in Brussels during a protest at a makeshift camp at the Greek-Macedonian border near the village of Idomeni on March 22, 2016. Greece will not be able to start sending refugees back to Turkey from March 20, 2016, the government said, as the country struggles to implement a key deal aimed at easing Europe's migrant crisis. The numbers are daunting: officials said as of Saturday there were 47,500 migrants in Greece, including 8,200 on the islands and 10,500 massed at the Idomeni camp on the Macedonian border. / AFP / ANDREJ ISAKOVIC (Photo credit should read ANDREJ ISAKOVIC/AFP/Getty Images)
After attacks in Brussels, a candle wrapped in a ribbon in the colors of the Belgium national flag and flowers are placed on a table inside the Belgium Embassy in Berlin, Germany, Tuesday, March 22, 2016. (AP Photo/Markus Schreiber)
Flowers are placed outside the embassy of Belgium, 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)
After deadly attacks on the Brussels airport and its subway system, a boy places a candle in front of the Belgian Embassy in Berlin, Germany, Tuesday, March 22, 2016. (AP Photo/Markus Schreiber)
MOSCOW, RUSSIA.MARCH 22, 2016. People bring flowers to the Belgian Embassy in Moscow to pay tribute to the Brussels terror attacks victims. On March 22, 2016, two explosions rocked Zaventem Airport and one blast struck a metro station. Mikhail Japaridze/TASS (Photo by Mikhail Japaridze\TASS via Getty Images)
MOSCOW, RUSSIA.MARCH 22, 2016. People bring flowers to the Belgian Embassy in Moscow to pay tribute to the Brussels terror attacks victims. On March 22, 2016, two explosions rocked Zaventem Airport and one blast struck a metro station. Alexander Shcherbak/TASS (Photo by Alexander Shcherbak\TASS via Getty Images)
A man lights a candle where flowers have being laid outside the Belgian embassy in Berlin on March 22, 2016. Security was tightened across Europe and transport links paralysed after a series of apparently coordinated explosions ripped through Brussels airport and a metro train, killing at least 34 people. / AFP / ODD ANDERSEN (Photo credit should read ODD ANDERSEN/AFP/Getty Images)
A wreath is layed on a table along flowers and a candle inside the Belgium embassy in Berlin on March 22, 2016 as the national and EU flag is reflected in the window. People left tributes to the victims outside the embassy after a series of apparently coordinated blasts ripped through Brussels airport and a train. / AFP / ODD ANDERSEN (Photo credit should read ODD ANDERSEN/AFP/Getty Images)
A man looks at flowers and a sign reading (Defy terror, protect freedom) outside the Belgium embassy in Berlin on March 22, 2016. People left tributes to the victims outside the embassy after a series of apparently coordinated blasts ripped through Brussels airport and a train. / AFP / ODD ANDERSEN (Photo credit should read ODD ANDERSEN/AFP/Getty Images)
MOSCOW, RUSSIA.MARCH 22, 2016. People bring flowers to the Belgian Embassy in Moscow to pay tribute to the Brussels terror attacks victims. On March 22, 2016, two explosions rocked Zaventem Airport and one blast struck a metro station. Alexander Shcherbak/TASS (Photo by Alexander Shcherbak\TASS via Getty Images)
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The Pinczowskis hadn't been heard from since their phone line went dead during the bombings. Cain said an "identity match" had been confirmed for them.

Related: John Kerry: We're Determined to Thwart Foreign Fighters

According to friends. the family had spent some time living in Germany.

Alex Kneeshaw, who has known the Pinczowskis for more than 15 years, told theNew York Daily News that Sascha was her best friend.

"We lived in Germany together, where I met the whole family and have been a part of it ever since. She is the kindest, goofiest, and (most) down-to-Earth girl I have ever met," she told the paper.

"She is the only friend that after a year or two of not seeing her we could sit down and act like no time had passed," Kneeshaw said. "When I moved back to America, Sascha came and stayed with me for two weeks to help with the move and support such a big change for me."

Another friend, Mark Lewis, told People Magazine the siblings were "very close" with each other.

"They are sweet and wonderful people," he said, adding that Alexander was an "incredibly friendly, dog-loving person" who had a lot of friends and had a passion for cooking.

Sascha graduated from Marymount Manhattan College in 2014, according to aLinkedIn page that appeared to belong to her. She had recently been a production intern for Shiraz Events, a New York events company, and had also been an event production intern at UNICEF.

The family has not spoken publicly since news of Sascha and Alexander's deaths. On Thursday, after being informed that Sascha and Alexander weren't on the list of wounded victims, the family thanked the Dutch Embassy and Delta Airlines for their help.

"We especially thank all of our friends and family, across two continents, for their expressions of love, support and prayers for Sascha and Alex. We ask for continued prayers and privacy during this time of grieving as we await final closure."

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