BEIJING (AP) — An explosion in a restaurant in northwestern China on Monday killed at least seven people and injured another 31, state media said.

The explosion happened at the start of the morning rush hour in a fast-food restaurant in Xi’an, the capital of Shaanxi province, according to a report on the website of the Xi’an Daily, which is run by Communist Party’s local propaganda department.

The website and the official Xinhua News Agency said the blast was likely caused by a natural gas leak. The explosion knocked out windows as far a mile (about two kilometers) away.

Photos online showed the front of a building had been blown into a street, where there were bodies covered in blue plastic.

Many of the victims, including children, were walking by the front of the restaurant or waiting for a bus, the website said.

Xinhua quoted a doctor as saying many were injured with wounds to the face and head.