A gas explosion at a coal mine in China’s northern province of Shanxi killed at least 82 people, state media reported Saturday and after dozens were said to be trapped underground.

Official news agency Xinhua said the accident at Changzhi city’s Liushenyu coal mine happened on Friday evening and 247 workers were trapped underground.

The agency initially reported early Saturday eight people were killed and 38 were trapped underground.

The cause of the explosion was under investigation, Xinhua reported, and rescue work is pressing on.

Chinese President Xi Jinping has called for an all-out effort to rescue the missing and an investigation of the accident's cause while holding those responsible accountable, according to Xinhua.

Shanxi province is known as China’s main coal mining province. With a size larger than Greece and a population of around 34 million, the province's hundreds of thousands of miners dug 1.3 billion tons (1.17 billion metric tons) of coal last year, or almost a third of China’s total.