Thailand bus accident leaves 18 dead, police say

"It was a downhill road and the brakes failed, and the driver lost control of the vehicle before it overturned," said Colonel Sophon Phramaneehe, adding that those who died were adults on a study trip.

Social media posts showed rescue and medical workers at the scene, 155 km (96 miles) east of the capital Bangkok, helping victims near the overturned bus with its under carriage exposed.