A series of bombing and arson attacks in southern Thailand that killed four people and wounded dozens was orchestrated by a single person, according to Thai police.
They said that two men have been held for questioning over the blasts in Hua Hin - a resort town struck by four bombs.
A third man is being questioned over a suspected arson attack in the southern province of Nakhon Si Thammar.
Officers, who have ruled out terrorism, said the investigation was preliminary and refused to identify the detained as suspects, or offer a possible motive.
"These acts were undertaken by a group in many areas simultaneously, following orders from one individual," a deputy national police chief, told reporters.
No one has claimed responsibility for at least 11 small explosives and series of suspected arson attacks that ripped across core tourist hubs on Thursday night and Friday morning, killing four locals and wounding dozens, including European tourists.
Thailand has also been wracked by a bitter power struggle between a military-allied elite and populist forces loyal to the ousted government.
The recent blasts, many of them detonated by mobile phones, came as an affront to a junta that prides itself on bringing a measure of stability to Thailand since its 2014 power grab.
The wave of attacks came as tourists flocked to the beaches at the start of a public holiday.
Police believe that more than one individual was involved in the attack on a supermarket in Nakhon Si Thammarat.
They said that the movements of other suspects were being monitored.
In Phang Nga, two devices that authorities believe failed to go off were found on Saturday near a market that was torched in an attack early on Friday.
"One worked and the other two didn't," the governor of Phang Nga, told Reuters, adding that police hoped to find fingerprints on the defused devices.
