China coal mine roof collapse kills 21

At least 21 miners died when a roof collapsed in a coal mine in northern China, officials say, according to BBC on Sunday.
Sixty-six miners were rescued after the accident on Saturday at the Lijiagou mine near the city of Shenmu in Shaanxi province.
The cause of the collapse is under investigation, the official Xinhua news agency reported.
Mining accidents in China are quite common despite efforts to improve safety.
The Lijiagou mine is operated by the Baiji Mining Company, Xinhua said.
Last October, 21 coal miners were killed when an underground rock fall blocked a shaft in eastern Shandong province.