The bus was traveling in Hunan province when the accident happened, Xinhua reported.
Most of the passengers were students heading to a school in Daxian county, where they were scheduled to attend an exam.
Two passengers have been confirmed dead. Several others were seriously injured and sent to a local hospital.
The director of the municipal work safety administration has been sent to the scene of the accident, the report said.
The cause of the crash was not reported.