The Loei-Nakhon Ratchasima coach of Nakornchai Transport Co Ltd lost balance and turned over at Km 13 of Ban Na-Kaeng Khoi road in the central province, according to Thai media reports.
It also hit the houses of people along the road and toppled lamp posts, causing a blackout in the area.
The driver told the police it was raining when the accident happened and that part of the road was a curve.
The injured passengers were sent to Kaeng Khoi Hospital. One of them sustained critical injuries.