The accident occurred Friday afternoon when a coach rolled over after rear-ending a car at the Tianjin section of an expressway linking the city's Binhai New Area with the city of Baoding in neighbouring Hebei Province, Xinhua reported.
Most of the passengers were students from the Hebei-based Tangshan College who were on their way back on the last day of the week-long National Day holiday that ended Friday, police said.
The injured had been rushed to local hospitals for treatment and the coach driver is in coma, according to the police.
Wang Qiang, an official with the city's traffic management bureau, said the coach was speeding and many passengers were thrown out of the vehicle when it hit the car and rolled over.