More than 20 people also injured after a double-decker bus collided with a truck in central Saraburi province.
A pre-dawn bus crash in central Thailand, Saraburi province, has killed 19 people and injured more than 20. An 18-wheeler truck hit the double-decker bus which then caught fire, on Tuesday.
Police say the truck drove through a barrier in the centre of the road and swerved into the path of oncoming traffic on the other side.
The driver of the truck was slightly injured and is being questioned by police.
The driver of the bus, which was travelling from Bangkok to Roi Et in the northeast of the country, was killed.
Images from Thai television news showed the extent of the damage to the vehicle, which appeared to have been completely incinerated and reduced to its metal shell.
Safety standards are often poor in Thailand and transport accidents are relatively common.
Earlier this month an overnight sleeper train travelling from Bangkok to the northern city of Chiang Mai derailed injuring 23 people, including 18 foreign tourists.
In April, at least five people were killed, including a seven-month-old baby and a Belgian woman, and 53 were injured when a Thai tour bus plummeted off a hillside in northern Phitsanulok province after its brakes failed.