The gas explosion occurred late on Friday at the Liushenyu coalmine in Qinyuan county, Shanxi province, with 247 workers on duty underground, state media Xinhua reported.
The mine is operated by Shanxi Tongzhou Group Liushenyu Coal Industry, which was established in 2010 and is controlled by Shanxi Tongzhou Coal Coking Group, according to corporate database Qichacha.
Rescue operations were ongoing and the cause of the accident was under investigation, according to the local emergency management authority in Qinyuan.
Shanxi is China's coalmining heartland.
President Xi Jinping called for authorities to "spare no effort" in treating the injured and conducting search and rescue operations, while ordering a thorough investigation into the cause of the accident and strict accountability in accordance with the law, according to Xinhua.
Premier Li Qiang called for timely and accurate release of information and rigorous accountability.
China has significantly reduced coalmine fatalities - often caused by gas explosions or flooding - since the early 2000s through more stringent regulations and safer practices.
In 2009, a coal and gas outburst in Heilongjiang Province killed 108 people and injured 133.
Executives of the company responsible for the mine had been detained, Xinhua reported.
Shanxi provincial authorities had dispatched seven rescue and medical teams totalling 755 personnel to the site, the emergency management bureau at Qinyuan said.
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