At least 14 people died and 35 others injured as a passenger tour bus veered off the road and collided with a tree in south Thailand's Prachuap Khiri Khan province.
The bus was travelling from the national capital Bangkok to Nathawi district, Songkhla province, local media reported on Tuesday.
The front part of the bus split in two by the force of the crash.
Arnon Tangto, a police investigator in Huay Yang district in Prachuap Khiri Khan said the cause of the accident has not been confirmed, but police suspect the driver, who was badly injured but survived may not have had enough sleep.
Thailand has one of the highest road accident rates in the world with around 20,000 people killed every year, according to the World Health Organization.
