Beijing - A gas explosion killed 23 people and left four trapped underground at a coal mine in north-eastern China's Liaoning province on Thursday, state media said.

Rescuers were trying to reach the four missing miners in the Qinghemen district of Liaoning's Fuxin city after the explosion on Thursday morning, the official Xinhua news agency said.

Accidents kill an estimated 10,000 people annually in Chinese mines. The accidents are often triggered by outdated equipment and poor safety measures, with many occurring at illegal mines. (dpa)