At least 82 people have been killed and two are missing after a coal mine blast in northern China. The gas explosion at the Liushenyu Coal Mine in Shanxi province is the worst mining disaster in China since 2009.

There were 247 workers reportedly on duty when the blast happened on Friday. According to the state media, most were affected after inhaling poisonous gas, though it is not clear what type of gas it was.

Local officials have also ordered immediate safety inspections of coal mines across Shanxi province.

The cause of the gas explosion has not yet been revealed, but state media reported that the levels of carbon monoxide – a highly toxic, odourless gas – in the mine were found to have exceeded limits. Chinese President Xi Jinping said that no effort should be spared to treat the injured and search for survivors.