Eighteen people were killed and 31 others injured in a bus accident in eastern Thailand on Wednesday, authorities said.

The accident occurred early Wednesday in Prachinburi province when a double-decker bus carrying 49 people on a study tour lost control and overturned on a downhill road, the local public relations office said.

The injured were taken to the nearest hospital for treatment.

Preliminary investigations suggest a brake system failure may have caused the accident.