21 dead in China coal mine accident

Four miners were rescued by emergency workers, Xinhua News Agency said. Seven managed to escape on their own after the accident Saturday at the Wujiu coal mine outside Datong city in Shanxi province, it said.

All of the victims died of carbon monoxide poisoning, Xinhua reported, citing an unidentified city official. The number of miners underground at the time of the accident was not known and rescuers were continuing to search, it said.

Xinhua said a preliminary investigation into the accident showed it was probably caused by an explosion.

The Wujiu mine is a registered operation with an annual production capacity of 150,000 tons, the agency said.

China's mines are the world's deadliest, with explosions, cave-ins and floods killing nearly 3,800 people last year.