Still, police still are looking for the main suspect, a man in a yellow T-shirt and dark-framed glasses. Authorities describe him as an unidentified foreigner who was caught on surveillance video hiding a backpack under a bench at the shrine minutes before the bomb detonated.
At least 10 people may have taken part in the bombing, but the attack is unlikely to be linked to international terrorist groups, Thai authorities say.
Royal Thai Police Commissioner Gen. Somyot Poompanmoung said Thursday he believes "several teams" were involved in the preparation and execution of the attack, which killed at least 20 people and wounded more than 120.
"This operation was carried out by a big network," he said.