No-one has said they carried out the attack but police have released a detailed sketch of the main suspect. The man was earlier pictured on CCTV, dressed in a yellow shirt, leaving a backpack at the shrine.
The Thai authorities said the suspect was a foreigner and that he was working as part of a network of 10 or more people.
But they said the bombing was "unlikely" to be the work of an international terror group, and that they did not believe Chinese tourists had been specifically targeted, who made up most of the foreigners killed