At least 20 people were killed Wednesday in a school bus accident in northwest China.

Officials said an overloaded minibus with more than 60 children and two adults on board collided with a coal truck in the city of Qingyang in Gansu province.

China's state-run Xinhua news agency quoted the local safety bureau as saying that five people died at the scene, while 15 others, their teacher included, were confirmed dead by the afternoon.

The statement said another 44 children were injured in the accident and have been hospitalized. Twelve of the injured are in a serious condition.

Xinhua says the bureau blamed overloading, saying in a statement that the nine-seat bus had 64 people on board at the time of the accident.

Road accidents are frequent in China mostly due to poor enforcement of safety standards.