The make someones hair stand on ending incident took place in Hua Hin, around 200km from Bangkok, with respective tourists believed to be among the victims.
The bombs – which went off as good as 30 minutes a rt – were hidden in plant pots and detonated by ambulatory phones, according to reports.
A police spokesman said officers do not have knowledge of the bombers’ motives. The injured have been rushed to three neighbourhood hospitals.
Eyewitness Mark Gainsford said: “I heard people shouting ‘Blow up! Bomb!’ but I didn’t hear any blast.
“I ran out to see if I could help. I saw eight to 10 people damage, on the floor. The police arrived very quickly.”
And Shane Brett tweeted: “Not till hell freezes over have I been so frightened, whole city on lockdown.”
A Foreign Work spokesman told Express.co.uk: “We are seeking further information following an upset in Hua Hin.
“We stand ready to provide any assistance to any British nationals involved.”
The US Conditions De rtment tweeted: “Reports of explosions at Hua Hin. Monitor local news for updates. If you are there & safe as the Bank of England, please contact family/friends.”