The State Administration of Work Safety says the bus plunged into a river following Saturday's midmorning accident in Wanlang township on the outskirts of Baishan city in Jilin province.
The official Xinhua News Agency put the death toll at 21. There was no immediate explanation for the discrepancy.
China's roads are the scene of frequent serious traffic accidents as a result of dangerous driving, bad roads and poorly maintained and overloaded vehicles.