HOHHOT - At least four people were dead and five others missing after a coal mine blasted in North China's Inner Mongolia autonomous region, local authorities said Monday.

The accident happened at around 3:00 am Monday in a coal mine belonging to Xingya Coal Development Co., Ltd. of Urad Front banner, Bayannur city, sources with Inner Mongolia's work safety supervision bureau said.

The blast, believed to be triggered by gas leak, occurred at a digging platform in the mine shaft.

Rescuers are racing to locate the missing miners, and an investigation into the blast is under way, said Wang Junyi, the bureau's director.