BANGKOK -- 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.

According to a local road safety center, 49 people were on the vehicle when it flipped over at about 3:00 am local time, and 16 people were killed on the spot.

The injured people were taken to the nearest hospital for treatment.

Local media quoted police as saying that the road was an accident-prone area. Preliminary investigations suggested that the accident may be caused by brake system failure.