A fire at a coal mine in northern China has killed 11 workers. Two others are missing.

The official Xinhua News Agency reported Friday that the workers at the coal mine in Zhangjiakou city died from carbon monoxide poisoning when an air compressor caught fire underground.

There were 13 miners underground when the fire started.

China's mines are notoriously deadly, with 1,384 people killed in coal mine accidents last year.

Safety improvements have reduced deaths in recent years, but regulations are often ignored and accidents are still common.