Police release sketch of Bangkok bomb suspect, offer reward

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Thai Police Suspect Bangkok Bomber Did Not Act Alone

BANGKOK (AP) — Police in Thailand released a sketch Wednesday of the man they believe carried out this week's deadly Bangkok bombing, and offered a 1 million baht ($28,000) reward for help leading to his arrest. But apart from a rough portrait, authorities have few solid leads — they don't know the bomber's motive, where he's from or if he's still in the country.

The sketch was released after grainy security video footage showed the man leaving behind a backpack just 15 minutes before the blast at a popular downtown shrine. Police said the picture was also partly based on a description provided by a motorcycle taxi driver believed to have given him a ride on the night of the Monday blast.

Two days after the attack, which authorities have called the worst in Thai history, the open-air Erawan Shrine reopened to the public. But little is known about who carried out the blast that left 20 people dead and more than 120 injured, and no one has claimed responsibility.

Police chief Somyot Poompanmoung said authorities didn't know if the suspect seen in the video was still in the country, whether he was Thai or a foreigner and were wondering if he wore a disguise to mask his identity.

The sketch released Wednesday showed a young man in eyeglasses with bushy, dark hair that is cropped at the sides.

See photos of the sketch and the explosion site:

48 PHOTOS
Bangkok, Thailand explosion
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Police release sketch of Bangkok bomb suspect, offer reward
Police examine debris in front of the Erawan Shrine at Rajprasong intersection in Bangkok, Thailand, Tuesday, Aug. 18, 2015, as investigations continue the morning after an explosion. Police combed through shattered glass and other debris Tuesday from a bomb blast in central Bangkok, trying to determine who set off the most devastating single attack in the capital's recent history. (AP Photo/Sakchai Lalit)
Investigators walk towards the Erawan Shrine at Rajprasong intersection in Bangkok, Thailand, Tuesday, Aug. 18, 2015, the morning after an explosion. Thailand's prime minister on Tuesday promised that authorities would quickly track down those responsible for the central Bangkok bombing, which he described as the country's worst attack ever. (AP Photo/Sakchai Lalit)
An investigator works near the statue of Phra Phrom, the Thai interpretation of the Hindu god Brahma, at the Erawan Shrine at Rajprasong intersection the day after an explosion in Bangkok, Thailand, Tuesday, Aug. 18, 2015. Thailand's prime minister on Tuesday promised that authorities would quickly track down those responsible for the central Bangkok bombing which he described as the country's worst attack ever. (AP Photo/Sakchai Lalit)
This combination of images taken from video on Monday, Aug. 17, 2015, and provided by MGTV shows people walking on an elevated skywalk as an explosion occurred in Bangkok, Thailand. Thailand's prime minister has promised to track down those responsible for the central Bangkok bombing which he described as the country's worst attack in history. (MGTV via AP) MANDATORY CREDIT
Police and soldiers wash the street in front of the Erawan Shrine at Rajprasong intersection the day after an explosion in Bangkok, Thailand, Tuesday, Aug. 18, 2015. Thailand's prime minister on Tuesday promised that authorities would quickly track down those responsible for the central Bangkok bombing which he described as the country's worst attack ever. (AP Photo/Sakchai Lalit)
Workers clean up the area around the statue of Phra Phrom, center, which is the Thai interpretation of the Hindu god Brahma, at the Erawan Shrine the day after an explosion in Bangkok, Thailand Tuesday, Aug. 18, 2015. Thailand's prime minister on Tuesday promised that authorities would quickly track down those responsible for the central Bangkok bombing which he described as the country's worst attack ever. (AP Photo/Sakchai Lalit)
The Erawan Shrine, right, and Rajprasong intersection remains closed in Bangkok, Thailand, Tuesday, Aug. 18, 2015, as investigations continue the morning after an explosion. Thailand's prime minister on Tuesday promised that authorities would quickly track down those responsible for the central Bangkok bombing which he described as the country's worst attack ever. (AP Photo/Sakchai Lalit)
Soldiers move onlookers back from the shattered windows of a Louis Vuitton shop at Gaysorn shopping plaza across from the Erawan Shrine at Rajprasong intersection in Bangkok, Thailand, Tuesday, Aug. 18, 2015, as investigations continue the morning after an explosion. Thailand's prime minister on Tuesday promised that authorities would quickly track down those responsible for the central Bangkok bombing, which he described as the country's worst attack ever. (AP Photo/Sakchai Lalit)
Police use a magnetic tool as they examine debris in front of the Erawan Shrine at Rajprasong intersection in Bangkok, Thailand, Tuesday, Aug. 18, 2015, as investigations continue the morning after an explosion. Police combed through shattered glass and other debris Tuesday from a bomb blast in central Bangkok, trying to determine who set off the most devastating single attack in the capital's recent history. (AP Photo/Sakchai Lalit)
This Aug. 17, 2015, image, released by Royal Thai Police spokesman Lt. Gen. Prawut Thavornsiri shows a man wearing a yellow T-shirt near the Erawan Shrine before an explosion occurred in Bangkok, Thailand. Prawut said he believes the man is a suspect in the blast that killed a number of people at a shrine in downtown Bangkok on Monday night. (Royal Thai Police via AP)
This image released by the Royal Thai Police on Wednesday, Aug. 19, 2015, shows a detailed sketch of the main suspect in a bombing that killed a number of people at the Erawan shrine in downtown Bangkok, on Monday. Thailand's national police chief said Wednesday that a deadly bombing at a central Bangkok shrine was carried out by "a network," as investigators focused on a man seen in a grainy security video leaving a backpack behind just 20 minutes before the explosion. The message above the sketch says "Criminal record registration department." (Royal Thai Police via AP)
This Aug. 17, 2015, image, released by Royal Thai Police spokesman Lt. Gen. Prawut Thavornsiri shows a man wearing a yellow T-shirt near the Erawan Shrine before an explosion occurred in Bangkok, Thailand. Prawut said he believes the man is a suspect in the blast that killed a number of people at a shrine in downtown Bangkok on Monday night. (Royal Thai Police via AP)
BANGKOK, THAILAND - AUGUST 19: The Erawan Shrine seen from the BTS walkway on August 19, 2015 in Bangkok, Thailand. On Monday evening Bangkok was hit by what has been described as Thailand's worst ever attack. Security across the country has been stepped up following the explosion which went off near a popular tourist site killing at least 20 people and injuring hundreds more. (Photo by Nicolas Axelrod/Getty Images)
Police investigate a scene the morning after an explosion in Bangkok,Thailand, Tuesday, Aug. 18, 2015. A bomb exploded Monday within a central Bangkok shrine that is among the city's most popular tourist spots, killing a number of people and injuring others, police said. (AP Photo/Mark Baker)
Police investigate a scene the morning after an explosion in Bangkok,Thailand, Tuesday, Aug. 18, 2015. A bomb exploded Monday within a central Bangkok shrine that is among the city's most popular tourist spots, killing a number of people and injuring others, police said. (AP Photo/Mark Baker)
A policeman photographs debris from an explosion in central Bangkok, Thailand, Monday, Aug. 17, 2015. A large explosion rocked a central Bangkok intersection during the evening rush hour, killing a number of people and injuring others, police said. (AP Photo/Mark Baker)
Thai rescue workers transport damaged motorcycles from the scene of a bomb blast outside a religious shrine in central Bangkok late on August 17, 2015. At least 16 people were killed and dozens injured when a bomb exploded today outside a religious shrine in a bustling hub of the Thai capital popular with tourists, authorities said. AFP PHOTO / PORNCHAI KITTIWONGSAKUL (Photo credit should read PORNCHAI KITTIWONGSAKUL/AFP/Getty Images)
In this image taken from AP video, a man talks into a mobile phone after a large explosion rocked a central Bangkok intersection on Monday, Aug. 17, 2015, during the evening rush hour, killing a number of people and injuring others. (Photo via AP Video)
Motorcycles and debris are strewn across Rajprasong Intersection in front of the Erawan Shrine after an explosion in Bangkok, Monday, Aug. 17, 2015. A large explosion rocked a central Bangkok intersection during the evening rush hour, killing a number of people and injuring others, police said. (AP Photo/Sakchai Lalit)
A police officer stands in the middle of Rajprasong Intersection in front of the Erawan Shrine after an explosion in Bangkok, Monday, Aug. 17, 2015. A large explosion rocked a central Bangkok intersection during the evening rush hour, killing a number of people and injuring others, police said. (AP Photo/Sakchai Lalit)
BANGKOK, THAILAND - AUGUST 17: Police chief Somyot Poompanmoung is interviewed by the press at the scene of an explosion on August 17, 2015 in Bangkok, Thailand. A large explosion believed to a bomb has hit central Bangkok this evening with early reports suggesting at least 16 people have died and scores more have been injured. (Photo by Nicolas Axelrod/Getty Images)
BANGKOK, THAILAND - AUGUST 17: Policemen check with sniffer dogs at the scene of an explosion on August 17, 2015 in Bangkok, Thailand. A large explosion believed to a bomb has hit central Bangkok this evening with early reports suggesting at least 16 people have died and scores more have been injured. (Photo by Nicolas Axelrod/Getty Images)
BANGKOK, THAILAND - AUGUST 17: A policebooth with shattered windows near the scene of an explosion on August 17, 2015 in Bangkok, Thailand. A large explosion believed to a bomb has hit central Bangkok this evening with early reports suggesting at least 16 people have died and scores more have been injured. (Photo by Nicolas Axelrod/Getty Images)
Motorcycles and debris are strewn across Rajprasong Intersection in front of the Erawan Shrine after an explosion in Bangkok, Monday, Aug. 17, 2015. A large explosion rocked a central Bangkok intersection during the evening rush hour, killing a number of people and injuring others, police said. (AP Photo/Sakchai Lalit)
Explosive Ordnance Disposal officers enter the Erawan Shrine after an explosion in Bangkok, Monday, Aug. 17, 2015. A large explosion rocked a central Bangkok intersection during the evening rush hour, killing a number of people and injuring others, police said. (AP Photo/Sackchai Lalit)
Officials close off an intersection after an explosion in Bangkok, Monday, Aug. 17, 2015. A large explosion rocked a central Bangkok intersection during the evening rush hour, killing a number of people and injuring others, police said. (AP Photo/Sackchai Lalit)
Police investigate the scene after an explosion in Bangkok, Monday, Aug. 17, 2015. A large explosion rocked a central Bangkok intersection during the evening rush hour, killing a number of people and injuring others, police said. (AP Photo/Mark Baker)
Emergency personnel work at the scene after an explosion in Bangkok, Monday, Aug. 17, 2015. A large explosion rocked a central Bangkok intersection during the evening rush hour, killing a number of people and injuring others, police said. (AP Photo/Sackchai Lalit)
Thai soldiers inspect the scene after a bomb exploded outside a religious shrine in central Bangkok late on August 17, 2015 killing at least 10 people and wounding scores more. Body parts were scattered across the street after the explosion outside the Erawan Shrine in the downtown Chidlom district of the Thai capital. AFP PHOTO / PORNCHAI KITTIWONGSAKUL (Photo credit should read PORNCHAI KITTIWONGSAKUL/AFP/Getty Images)
Police investigate the scene at the Erawan Shrine after an explosion in Bangkok,Thailand, Monday, Aug. 17, 2015. A large explosion rocked a central Bangkok intersection during the evening rush hour, killing a number of people and injuring others, police said(AP Photo/Mark Baker)
Explosive Ordnance Division officers work at the scene after an explosion at an intersection in Bangkok, Monday, Aug. 17, 2015. A large explosion rocked a central Bangkok intersection during the evening rush hour, killing a number of people and injuring others, police said. (AP Photo/Sackchai Lalit)
In this image provided by Mongkol Nunthalikitkun flames burn after an explosion in Bangkok, Monday, Aug. 17, 2015. A large explosion rocked a central Bangkok intersection during the evening rush hour, killing a number of people and injuring others, police said. (Mongkol Nunthalikitkun via AP)
BANGKOK, THAILAND - AUGUST 17: A rescue worker walks past the scene of an explosion on August 17, 2015 in Bangkok, Thailand. A large explosion believed to be from a bomb has happened in central Bangkok this evening with early reports suggesting 12 people have died and at least 20 more have been injured. (Photo by Nicolas Axelrod/Getty Images)
Motorcycles and debris lies on the pavement after an explosion in Bangkok, Monday, Aug. 17, 2015. A large explosion rocked a central Bangkok intersection during the evening rush hour, killing a number of people and injuring others, police said. (AP Photo/Sackchai Lalit)
A Thai soldier (R) looks at the damage after a bomb exploded outside a religious shrine in central Bangkok late on August 17, 2015 killing at least 10 people and wounding scores more. Body parts were scattered across the street after the explosion outside the Erawan Shrine in the downtown Chidlom district of the Thai capital. AFP PHOTO / PORNCHAI KITTIWONGSAKUL (Photo credit should read PORNCHAI KITTIWONGSAKUL/AFP/Getty Images)
Thai rescue workers carry an injured person after a bomb exploded outside a religious shrine in central Bangkok late on August 17, 2015 killing at least 10 people and wounding scores more. Body parts were scattered across the street after the explosion outside the Erawan Shrine in the downtown Chidlom district of the Thai capital. AFP PHOTO / PORNCHAI KITTIWONGSAKUL (Photo credit should read PORNCHAI KITTIWONGSAKUL/AFP/Getty Images)
Motorcycles are strewn about after an explosion in Bangkok, Monday, Aug. 17, 2015. A large explosion rocked a central Bangkok intersection during the evening rush hour, killing a number of people and injuring others, police said. (AP Photo/Jerry Harmer)
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Thai police inspect the scene after a bomb exploded outside a religious shrine in central Bangkok late on August 17, 2015 killing at least 10 people and wounding scores more. Body parts were scattered across the street after the explosion outside the Erawan Shrine in the downtown Chidlom district of the Thai capital. AFP PHOTO / PORNCHAI KITTIWONGSAKUL (Photo credit should read PORNCHAI KITTIWONGSAKUL/AFP/Getty Images)
Police investigate the scene after an explosion in Bangkok, Monday, Aug. 17, 2015. A large explosion rocked a central Bangkok intersection during the evening rush hour, killing a number of people and injuring others, police said. (AP Photo/Sackchai Lalit)
Thai rescue workers transport an injured person after a bomb exploded outside a religious shrine in central Bangkok late on August 17, 2015 killing at least 10 people and wounding scores more. Body parts were scattered across the street after the explosion outside the Erawan Shrine in the downtown Chidlom district of the Thai capital. AFP PHOTO / PORNCHAI KITTIWONGSAKUL (Photo credit should read PORNCHAI KITTIWONGSAKUL/AFP/Getty Images)
A Thai soldier ropes off the scene after a bomb exploded outside a religious shrine in central Bangkok late on August 17, 2015 killing at least 10 people and wounding scores more. Body parts were scattered across the street after the explosion outside the Erawan Shrine in the downtown Chidlom district of the Thai capital. AFP PHOTO / PORNCHAI KITTIWONGSAKUL (Photo credit should read PORNCHAI KITTIWONGSAKUL/AFP/Getty Images)
Thai rescue workers transport an injured person (C) after a bomb exploded outside a religious shrine in central Bangkok late on August 17, 2015 killing at least 10 people and wounding scores more. Body parts were scattered across the street after the explosion outside the Erawan Shrine in the downtown Chidlom district of the Thai capital. AFP PHOTO / PORNCHAI KITTIWONGSAKUL (Photo credit should read PORNCHAI KITTIWONGSAKUL/AFP/Getty Images)
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#ErawanBlast — Police confirmed most of those injured are foreign tourists. #Bangkok
@RichardBarrow @duiwoy one more picture from a friend there #BangkokBombing #Bangkok http://t.co/e7QruuAuI7
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"If citizens or anyone can give us information or clues that leads to the arrest of this man I have set a reward of 1 million baht," Somyot told reporters, adding that police believe the bomber worked with accomplices.

"He didn't do it alone, for sure. It's a network," Somyot said. Police spokesman Lt. Gen. Prawut Thavornsiri said the security footage appears to show two possible accomplices who are also considered suspects.

On Tuesday, police released still photos of the man seen in the video, wearing a yellow T-shirt and shorts. His hair appears shaggier in the video than the police sketch. The photographs show him both with and without a large, black backpack. A video posted separately on Thai media showed the same man sitting on a bench at the shrine, taking off the backpack and leaving it behind as he stood up to fiddle with his phone and then walked away. Time stamps on the footage show that he left the shrine 15 minutes before the Monday night explosion, which struck just before 7 p.m.

The attack has raised concerns about safety in a city that draws millions of tourists and had never experienced an attack of this magnitude.

Prime Minister Prayuth Chan-ocha "is worried about the security of people and tourists in Thailand," the police chief said Wednesday before heading into a three-hour meeting of national police commanders.

Prayuth has called the attack "the worst incident that has ever happened in Thailand" and vowed to track down those responsible.

The site of the blast, the Erawan Shrine, is a revered spot among Thais and tourists that transcends religion. It is dedicated to the Hindu god Brahma, but is extremely popular among Thailand's Buddhists as well as Chinese tourists.

Although Thailand is predominantly Buddhist, Hinduism has an influence on its religious practices and language. The shrine's location adds to its popularity, offering an open-air place for prayer amid the capital's gleaming shopping malls and five-star hotels.

On Wednesday morning, a stream of people arrived at the Erawan Shrine, kneeling in prayer, lighting incense and placing flowers at the site where 36 hours earlier an explosion scattered body parts across one of the capital's busiest intersections. Buddhist monks in saffron robes joined members of the public to chant prayers at the popular Hindu shrine.

SEE ALSO: Memorials for the victims of the blast:

21 PHOTOS
Bangkok, Thailand memorials
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Police release sketch of Bangkok bomb suspect, offer reward
BANGKOK, THAILAND - AUGUST 19: People pray in front the Erawan Shrine on August 19, 2015 in Bangkok, Thailand. On Monday evening Bangkok was hit by what has been described as Thailand's worst ever attack. Security across the country has been stepped up following the explosion which went off near a popular tourist site killing at least 20 people and injuring hundreds more. (Photo by Nicolas Axelrod/Getty Images)
Monks make offerings at the reopened Erawan shrine in Bangkok on 19 August 2015. Thai monks led prayers for the reopening of Bangkok shrine where a blast killed 20 people, as police hunted a man shown on security footage calmly planting what is believed to be the bomb. AFP PHOTO / Jerome TAYLOR (Photo credit should read JEROME TAYLOR/AFP/Getty Images)
ERAWAN SHRINE, BANGKOK, KRUNG THEP MAHA NAKHON, THAILAND - 2015/08/18: A memorials are set up outside Erawan Shrine a day after a bomb exploded close to the shrine in the center of Thailand's capital, Bangkok, killing at least 22 people and injuring more than 125. Reports say a second bomb has been found in the area and made safe. No-one has yet said they carried out the attack, which took place close to the Erawan shrine in Bangkok's central Chidlom district. The shrine is a major tourist attraction. The Thai government said the attack was aimed at foreigners. Local media report that tourists, including Chinese, are among the casualties. (Photo by Stephen J. Boitano/LightRocket via Getty Images)
ERAWAN SHRINE, BANGKOK, KRUNG THEP MAHA NAKHON, THAILAND - 2015/08/18: A memorials are set up outside Erawan Shrine a day after a bomb exploded close to the shrine in the center of Thailand's capital, Bangkok, killing at least 22 people and injuring more than 125. Reports say a second bomb has been found in the area and made safe. No-one has yet said they carried out the attack, which took place close to the Erawan shrine in Bangkok's central Chidlom district. The shrine is a major tourist attraction. The Thai government said the attack was aimed at foreigners. Local media report that tourists, including Chinese, are among the casualties. (Photo by Stephen J. Boitano/LightRocket via Getty Images)
A woman prays at the Erawan Shrine at Rajprasong intersection in Bangkok, Thailand, Wednesday, Aug. 19, 2015. A central Bangkok shrine reopened Wednesday to the public after Monday's bomb blast as authorities searched for a man seen in a grainy security video who they say was the prime suspect in an attack authorities called the worst in the country's history. (AP Photo/Sakchai Lalit)
Mourners pray for the victims of a bomb blast at the reopened Erawan shrine in Bangkok, Thailand, on Wednesday, Aug. 19, 2015. Bangkok's deadly bomb attack this week is set to hit Thailand's last remaining growth pillar with travel warnings and canceled trips, adding pressure on authorities to restore confidence and stimulate the economy. Photographer: Dario Pignatelli/Bloomberg via Getty Images
ERAWAN SHRINE, BANGKOK, KRUNG THEP MAHA NAKHON, THAILAND - 2015/08/19: People visit Erawan Shrine after it reopened two days after a bomb exploded close to the shrine in the center of Thailand's capital, Bangkok, killing at least 22 people and injuring more than 125. CCTV shows a man leaving a backpack on a bench at the shrine minutes before the bomb exploded. No-one has yet said they carried out the attack, which took place close to the Erawan shrine in Bangkok's central Chidlom district. The shrine is a major tourist attraction. The Thai government said the attack was aimed at foreigners. Local media report that tourists, including Chinese, are among the casualties. (Photo by Stephen J. Boitano/LightRocket via Getty Images)
A woman prays at the Erawan Shrine at Rajprasong intersection in Bangkok, Thailand, Wednesday, Aug. 19, 2015. The central Bangkok shrine reopened Wednesday after Monday's bomb blast to the public as authorities searched for a man seen in a grainy security video who they say was the prime suspect in an attack authorities called the worst in the country's history. (AP Photo/Sakchai Lalit)
Thai office workers light candles for victims killed in a bomb blast outside a religious shrine in Bangkok on August 18, 2015. The death toll from a bomb blast in the Thai capital rose to 20 on August 18 with 123 wounded, police said, with eight tourists from China, Hong Kong, Indonesia, Malaysia and Singapore among those killed in the attack. AFP PHOTO / PORNCHAI KITTIWONGSAKUL (Photo credit should read PORNCHAI KITTIWONGSAKUL/AFP/Getty Images)
A Thai lights a candle near the Erawan Shrine at Rajprasong intersection the day after an explosion in Bangkok, Thailand, Tuesday, Aug. 18, 2015. Thailand's Prime Minister Prayuth Chan-ocha called Monday's explosion at the busy intersection "the worst incident that has ever happened in Thailand," and promised to track down those responsible. (AP Photo/Sakchai Lalit)
Thai office workers lay flowers for victims killed in a bomb blast outside a religious shrine in Bangkok on August 18, 2015. The death toll from a bomb blast in the Thai capital rose to 20 on August 18 with 123 wounded, police said, with eight tourists from China, Hong Kong, Indonesia, Malaysia and Singapore among those killed in the attack. AFP PHOTO / PORNCHAI KITTIWONGSAKUL (Photo credit should read PORNCHAI KITTIWONGSAKUL/AFP/Getty Images)
A Thai office worker lights candles for victims killed in a bomb blast outside a religious shrine in Bangkok on August 18, 2015. The death toll from a bomb blast in the Thai capital rose to 20 on August 18 with 123 wounded, police said, with eight tourists from China, Hong Kong, Indonesia, Malaysia and Singapore among those killed in the attack. AFP PHOTO / PORNCHAI KITTIWONGSAKUL (Photo credit should read PORNCHAI KITTIWONGSAKUL/AFP/Getty Images)
A woman lights a candle for the victims near the Erawan Shrine at Rajprasong intersection the day after an explosion in Bangkok, Thailand, Tuesday, Aug. 18, 2015. Thailand's Prime Minister Prayuth Chan-ocha called Monday's explosion at the busy intersection "the worst incident that has ever happened in Thailand," and promised to track down those responsible. (AP Photo/Sakchai Lalit)
Thai office workers lay flowers for victims killed in a bomb blast outside a religious shrine in Bangkok on August 18, 2015. The death toll from a bomb blast in the Thai capital rose to 20 on August 18 with 123 wounded, police said, with eight tourists from China, Hong Kong, Indonesia, Malaysia and Singapore among those killed in the attack. AFP PHOTO / PORNCHAI KITTIWONGSAKUL (Photo credit should read PORNCHAI KITTIWONGSAKUL/AFP/Getty Images)
Messages of condolence are left for victims of the bomb blast at Rajprasong intersection near the Erawan Shrine in Bangkok, Thailand, Tuesday, Aug. 18, 2015. Thailand's prime minister on Tuesday promised that authorities would quickly track down those responsible for the central Bangkok bombing which he described as the country's worst attack ever.(AP Photo/Sakchai Lalit)
BANGKOK, THAILAND - AUGUST 18: People leave flowers near the site of a blast at the Erawan Hindu shrine at the Ratchaprasong intersection in Bangkok, Thailand, on Tuesday, August 18, 2015. The death toll rise to at least 21 and 123 injured from the deadly blast in Central Bangkok last night. (Photo by Guillaume Payen/Anadolu Agency/Getty Images)
A Thai office worker holds flowers for victims killed in a bomb blast outside a religious shrine in Bangkok on August 18, 2015. The death toll from a bomb blast in the Thai capital rose to 20 on August 18 with 123 wounded, police said, with eight tourists from China, Hong Kong, Indonesia, Malaysia and Singapore among those killed in the attack. AFP PHOTO / PORNCHAI KITTIWONGSAKUL (Photo credit should read PORNCHAI KITTIWONGSAKUL/AFP/Getty Images)
Thai office workers lay flowers for victims killed in a bomb blast outside a religious shrine in Bangkok on August 18, 2015. The death toll from a bomb blast in the Thai capital rose to 20 on August 18 with 123 wounded, police said, with eight tourists from China, Hong Kong, Indonesia, Malaysia and Singapore among those killed in the attack. AFP PHOTO / PORNCHAI KITTIWONGSAKUL (Photo credit should read PORNCHAI KITTIWONGSAKUL/AFP/Getty Images)
Thai people light candles in front of notes of condolence for the victims near the Erawan Shrine at Rajprasong intersection the day after an explosion in Bangkok, Thailand, Tuesday, Aug. 18, 2015. Thailand's Prime Minister Prayuth Chan-ocha called Monday's explosion at the busy intersection "the worst incident that has ever happened in Thailand," and promised to track down those responsible. (AP Photo/Sakchai Lalit)
Thai people light candles near the Erawan Shrine at Rajprasong intersection the day after an explosion in Bangkok, Thailand, Tuesday, Aug. 18, 2015. Thailand's Prime Minister Prayuth Chan-ocha called Monday's explosion at the busy intersection "the worst incident that has ever happened in Thailand," and promised to track down those responsible. (AP Photo/Sakchai Lalit)
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Among those who paid respects was an office worker, Nuansupha Sarunsikarin, who expressed shock and sadness over the attack, which no one has claimed responsibility for. Authorities say it came by surprise, with no clear motive.

"I'm depressed for those innocent people who had to pay for something they're not involved with and now have no chance to live their lives," Nuansupha said.

Thai authorities identified six victims as Thai and four Malaysians, along with four Chinese, two people from Hong Kong, one Indonesian and one Singaporean. Two victims remain unidentified.

Bangkok was rattled by a second blast Tuesday at a popular ferry pier, which exploded in the Chao Phraya River and caused no injuries. Prawut said Tuesday's blast at the Sathorn Pier frequented by river ferries and tourist boats also was caused by a pipe bomb and could be related to the shrine attack. Security video showed a sudden blast of water over a walkway at the pier as bystanders ran for safety.

Thailand has seen many violent attacks in recent years, particularly in a more-than-decade-long insurgency by Muslim separatists that has killed over 5,000 in the country's south. Those attacks have never reached the capital, however.

Bangkok has seen politically charged violence in the past decade; the deadliest, in 2010, killed more than 90 over two months and was centered on the same intersection where Monday's bomb went off. But none of those attacks included a bomb that seemed intended to produce mass casualties.



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