At least 19 people were killed and more than 50 injured on Friday when a bus carrying university students crashed in eastern Thailand, a police officer said.
"Nineteen bodies are retrieved and I saw at least three more bodies trapped under the bus. I fear that there may be more victims after we lift the bus," local police officer Major Akkapark Jitprayoon told AFP.
"The accident may have been caused by the driver, who is presumed killed."
A highway police officer in eastern Prachinburi province, where the accident happened, said they suspected the driver had fallen asleep at the wheel, as the bus overturned with no other apparent cause for the crash.
Sixteen men and three women were killed immediately in the accident 135 kilometres east of Bangkok, police said.
The charter bus was will filled with students from a technology university in northeastern Khon Kaen province.
They were travelling to a field trip in the coastal province of Chantaburi when the bus overturned at 3:30 am (0200 IST).
Injured passengers were taken to three nearby hospitals. It was not immediately clear how many were wounded, with police saying only at least 50 were being treated.