Eighteen people were killed and 32 others injured when a bus taking people on a community study tour overturned on a downhill road in Nadi district of Prachin Buri early on Wednesday.

The bus was one of three taking about 200 people from Bueng Kan province, beside the Mekong River, to Rayong.

The accident happened around 3.20am on Highway 304. The driver lost control on a downhill section, the bus plunged off the road down a slope and overturned. 

Reports said 17 people died at the scene and another died later at a hospital. 

Of the 32 injured, 19 were taken to Nadi Hospital and 13 to Kabin Buri Hospital.

Police were investigating the cause of the accident.