All of the victims were on board the bus, which belonged to a local public transport company, Wudalianchi Passenger Transport Company.
It is not immediately known whether the bus driver was killed or injured.
The bus had a capacity of 35 people, but was apparently overloaded, judging from the casualties. Further investigation is under way to determine how many passengers were on the bus at the time of the collision.
The train, operated by a local railway company in Heihe, has left the scene. The railway line resumed operation at around 11 a.m. on Monday.