The 47-seat bus was approaching its destination in Nanning, capital of Guangxi, when it met with the accident on a highway yesterday, police said.
The bus driver was among those killed. Thirty-two people were injured, five of whom seriously, police said.
Ling Minhui, an injured passenger, said she was waken up when the bus rammed into guardrails.
“All passengers were seated, but most did not fasten their seat belts,” she said.
The injured were sent to nearby hospitals, state-run Xinhua news agency reported.
The five seriously injured suffered brain and lumbar spine injuries, a doctor at the First Affiliated Hospital of Guangxi Medical University said, adding that one was in life- threatening condition.
Initial investigations showed the accident might have been triggered by a sudden health condition on part of the driver.
Further probe was under way.
The accident initially triggered a traffic snarl, but it was eased later by officials.
PTI