A wave of coordinated explosions rattled multiple cities across southern Thailand, killing at least four people and wounding dozens more. Among the injured were 10 foreigners in the seaside resort town of Hua Hin.
It was not clear who was behind the attacks, but police said the violence was not linked to Islamic terrorism.
The timing and scope suggested the bombs were set off by opponents of the Southeast Asian nation's ruling junta, which last weekend organized a successful referendum on a constitution that critics say will bolster the military's power for years to come.
Friday is also a public holiday in Thailand to mark Queen Sirikit's birthday.
Britain and Australia reacted to the news by advising their nationals to avoid public places.
Where has been targeted?
The explosions all occurred south of Bangkok and several of the blasts - including one on Patong beach in the tourist resort of Phuket - appeared designed to hit the tourism industry.
The first two explosions occurred overnight on a busy street in the tourist city of Hua Hin, which was hit again by another blast on Friday morning. The city is home to a swath of beachfront resorts as well as a royal palace.
Police and Thai media reported other blasts in the southern cities of Phuket, Trang and Surat Thani.
Who is behind the attacks?
So far, nobody has claimed responsibility for the attacks, and officials have said they do not know who is behind them.
Prime Minister Prayut Chan-O-Cha called for calm.
"The bombs are an attempt to create chaos and confusion," he told reporters. "We should not make people panic more."
Regardless of culprit, string of bomb attacks countrywide most wide reaching and coordinated attacks in recent Thai history.
"Why the bombs occurred as our country is heading towards stability, a better economy and tourism - and who did it - you have to find out for me," he added.
Royal Thai Police official Col Krisana Patanacharoen said it was too soon say who was behind the attacks, but "we are sure that it is not linked to terrorism."
Hua Hin's district chief, Sutthipong Klai-udom, told AFP that the first bombs were detonated by mobile phone. Staff at local hospitals said German, Italian, Dutch and Austrian nationals were among the wounded.
Sitthichai Srisopacharoenrat said the first victim who died was a Thai women. Initial reports on social media said she was a market vendor.
One eyewitness said a man and his child were badly injured in the attack and had "bones sticking out of their legs."
Another, a British man named Mark Gainsford, told the BBC: "I heard people shouting 'Bomb! Bomb!' but I didn't hear any blast."
"I ran out to see if I could help. I saw eight to 10 people injured, on the floor. The police arrived very quickly."
Source: Telegraph, 12 Aug. 2016