A gas explosion that ripped through a barbecue restaurant in northwestern China killed at least 31 people, officials said Thursday, hours after the blast had turned the restaurant into a charred ruin.

The explosion hit the two-story restaurant in Yinchuan, the capital of the Ningxia region, at 8:40 p.m. Wednesday, when it was busy with customers eating lamb kebabs and other dishes cooked on gas burners. Firefighters rushed to the scene, where thick smoke rose into the sky and shattered glass and debris covered the street. They put out the fire within an hour.

The scale of death became clear to the public only on the following morning, when the authorities announced the death toll and that seven other people were hospitalized with injuries, one in critical condition.