A chartered double-decker bus taking 47 registered Myanmar workers to Pathum Thani caught fire in Tak early on Friday, killing 20 of them trapped inside, police said.
Three other Myanmarians were injured when they jumped out of the bus while 24 others were able to get out in time and were not injured.
The Thai bus driver, his aide and his wife escaped uninjured.
The Mae Tho police station was alerted to the fire at 1am on the highway No. 12 in Tambon Mae Tho in Tak’s Muang district.
When police and firefighters arrived, the entire bus was engulfed in fire, which was quickly extinguished.
Rescuers found 20 bodies, which were charred beyond recognition, inside the bus.
Police said the 47 Myanmar workers had proper documents and were travelling from the border checkpoint in Tak’s Mae Sot district heading to the Navanakhon industrial estate in Pathum Thani.
Survivors said the fire started in the middle of the bus and spread quickly, trapping those in the back.