Thailand's defence minister has said those who planted a bomb at a Bangkok shrine deliberately targeted foreigners to harm tourism and the economy.
Prawit Wongsuwan vowed to hunt down the perpetrators of the attack in the capital, which killed at least 21 people and injured more than 120.
The Erawan Shrine is a major tourist attraction and foreigners are among the casualties.
The attack has not been claimed and it is unclear who would target the site.
The bomb was detonated at about 19:00 local time (12:00 GMT) on Monday.
Live coverage of Bangkok aftermath
The Hindu shrine, and the busy Ratchaprasong junction where it is located, were crowded when the explosion occurred
Mr Wongsuwon told reporters that the bombers had "targeted foreigners... to damage tourism and the economy".
"We will hunt them down," Reuters quoted him as saying.
Prime Minister Prayuth Chan-ocha said the government was setting up a "war room" to co-ordinate its response, according to the Nation TV channel.
National police chief Somyot Poompummuang described the device as a "pipe bomb" and said it had been placed inside the shrine. Reports said 3kg of TNT had been used in the bomb.
"Whoever planted this bomb is cruel and aimed to kill. Planting a bomb there means they want to see a lot of people dead," he said.
Officials said 10 Thais had been confirmed dead, along with two Chinese and one Filipino. Thai police said 123 people had been injured.
Jonathan Head BBC News, Bangkok: "Who is behind this attack?"It is a shocking atmosphere in Bangkok. The police have left the scene and gathered what evidence they can, but people here can't remember anything of this scale happening before.
Bangkok is now sitting back and wondering who could possibly have carried out this act and what their motives could have been.
There is no shortage of potential suspects - people might wonder if it was the Muslim insurgency fighting for an independent state in the deep south. Lots of bombs go off there but, the insurgents have never perpetrated an attack outside their own area, so this would be an entire change in tactics.
People also look at the recent political violence and wonder if factions who lost out might have been involved.
It will be some time before the government gives some idea of what we should be looking for.
The BBC's Jonathan Head, who was one of the first journalists at the scene, said it was a chaotic sight, with body parts scattered everywhere.
Marko Cunningham, a New Zealand paramedic working with a Bangkok ambulance service, said the scene was "like a meat market".
"There were bodies everywhere. Some were shredded. It was horrific," he told the Reuters news agency.
The shrine is dedicated to the Hindu god Brahma, but is also visited by thousands of Buddhists each day.
It sits between a five-star hotel and a popular shopping centre on the Ratchaprasong intersection, which has been the centre of political demonstrations in recent years.
Bangkok has seen a decade of sometimes violent rivalry between political factions.
The military took over the country in May last year, removing an elected government following months of unrest. The capital has been relatively calm since then.
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