Thirty-one people were killed by a gas explosion at a barbecue restaurant in northwestern China on Wednesday night, the official Xinhua News Agency reported.

The explosion was caused by a leakage of liquefied petroleum gas at the restaurant, Xinhua said. It happened around 8:40 p.m. in Yinchuan, a city in the northern part of the Ningxia autonomous region. Seven other people are being treated for injuries, including one in critical condition.

Explosions caused by gas leaks at restaurants are a common occurrence in China. More than 20 people died in Chongqing last year at a blast in the canteen of a local government office.

President Xi Jinping demanded authorities make all efforts to treat the wounded and strengthen safety supervision in key industries and areas, state broadcaster China Central Television reported.