Rescuers, including police officers, paramedics from Khao Yoi Hospital and the Sawang Phet Dhammasathan Foundation rushed to the scene.
The bus slipped off Phet Kasem Road as it was making its way from Surat Thani to Bangkok.
Police said 18 of the 25 foreigners inside the bus were injured, adding that the passengers included young children around the age of 10.
“The passengers were given first aid before being transported to Khaoyoi Hospital,” police said.
Investigators believe the driver may have fallen asleep behind the wheel and have taken him in for interrogation.