Xinhua reported that the blast occurred on Saturday afternoon at the Qingxing coal mine in northeast China’s Jilin province while 73 people were working underground.

Of the 55 people lifted to safety, 12 sustained minor injuries and are being treated at a local hospital.

Mine officials are in custody after a preliminary investigation revealed the mine’s failure to remedy previously identified hazards, according to Xinhua.

It is the third coal mine gas explosion in the province in a month.

Repeat explosions on March 29 and April 1 at the Babao coal mine in Baishan City killed a total of 53 workers.