Thailand’s Prime Minister Prayuth Chan-ocha has said the bombing of a shrine in the capital, Bangkok, on Monday was the “worst-ever attack” on the country.
The attack killed at least 20 people, including at least eight foreigners.
Mr Prayuth said the perpetrators had not been identified, but police have released images of one suspect seen on security footage at the shrine.
In a separate attack in Bangkok, an explosive device was thrown from a pier but caused no injuries on Tuesday.
The device – possibly a grenade – appears to have been thrown at the busy Sathorn pier in Bangkok but landed in water where it exploded harmlessly.
“If it did not fall in the water then it certainly would have caused injuries,” the district’s deputy police chief Col Natakit Siriwongtawan told Reuters news agency.
Monday’s bomb targeted the Erawan Hindu shrine, a major tourist attraction.
It was detonated at about 19:00 local time (12:00 GMT) on Monday when the shrine, and the nearby Ratchaprasong junction, were crowded.
Scores of people were wounded.
“This is the worst incident that has ever happened in Thailand,” Mr Prayuth said.
“There have been minor bombs or just noise, but this time they aim for innocent lives. They want to destroy our economy, our tourism.”
Authorities are now examining video footage taken from several CCTV cameras around the shrine for clues, says the BBC’s Jonathan Head in Bangkok.
They have released images of one young man who appears to walk into the shrine wearing a black backpack, but is then seen walking without it.
Members of the public are also handing in their own video coverage.
Eyewitness accounts of the blast – “There was total chaos”
In pictures – scene of devastation
CCTV footage – captures the moment of the explosion
The facts – what we know so far
The Erawan Shrine – popular with locals and tourists
Mobile phone footage captures the blast
‘I gave one man CPR’ says BBC man
The bomb was clearly placed to cause maximum casualties, our correspondent says, and there is a lingering sense of shock in Thailand, which until now had been spared the kinds of terrorist incidents experienced by some of its neighbours.
Most victims were Thai, but at least eight were foreign – mostly from elsewhere in Asia.
In currency trading, the Thai baht fell to its lowest level in six years.
Jonathan Head BBC News, Bangkok: “Who is behind this attack?”
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.
National police chief Somyot Poompummuang earlier described the device as a pipe bomb – an improvised device where explosive material is put in a sealed cavity to maximise the explosive impact.
He said the 3kg bomb had been placed inside the shrine.
“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.
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.
Are you in Bangkok? Were you affected by the bomb attack? You can emailwith your story.
Please include a contact number if you are willing to speak to a BBC journalist. You can also contact us in the following ways: