HOHHOT - A passenger bus overturned on a highway in North China's Inner Mongolia autonomous region on Monday, killing four people onboard, the local government said.

The accident occurred around 9 am, when a coach carrying 20 people overturned near the Chaqi section of a highway linking the city of Rongcheng in East China's Shandong province and the city of Wuhai in Inner Mongolia, according to a statement from the autonomous region's Etuoke Banner government.

The bus was traveling from Inner Mongolia's Wulan Township to the city of Yinchuan, capital of the neighboring Ningxia Hui autonomous region.

The statement said three passengers were killed at the scene and another died in a nearby hospital, despite receiving medical treatment.

Fifteen people onboard were slightly injured in the accident.

Local police are investigating the cause of the accident.