At least 82 people have died, and several remain trapped underground after a gas explosion at the Liushenyu coal mine in China’s Shanxi province, state media reported Saturday.

The blast occurred at 7:29 p.m. Friday with 247 workers underground, of whom 201 had been brought to the surface safely by early Saturday morning.

What happened at the Liushenyu coal mine in Shanxi?

The gas explosion struck the Liushenyu mine in Qinyuan county at 7:29 p.m. Friday local time, according to state news agency Xinhua.

Carbon monoxide levels had “exceeded limits” at the mine, Xinhua reported, with some of those trapped underground described as being in “critical condition.”

“Reporters learnt from the scene of the gas explosion at the Liushenyu Coal Mine… that the accident has resulted in 82 deaths and nine people missing,” state broadcaster CCTV said.

What did President Xi Jinping say about the coal mine blast?

Xi urged “all-out efforts” to treat the injured and called for thorough investigations into the incident.

He “emphasized that all regions and departments must draw lessons from this accident, remain constantly vigilant regarding workplace safety and resolutely prevent and curb the occurrence of major and catastrophic accidents,” Xinhua reported.

How safe are China’s coal mines?

Shanxi, one of China’s poorer provinces, is the country’s coal-mining capital. Mine safety has improved in recent decades, but accidents still occur frequently in an industry where safety protocols are often lax.

China is the world’s top consumer of coal and the largest greenhouse gas emitter, despite installing renewable energy capacity at record speed.