The blast occurred at the Weijiadi coal mine in the city of Baiyin in Gansu, an underdeveloped province hosting part of the Gobi Desert, Xinhua reported, adding that rescue operations were underway.
The news agency quoted Jingyuan Coal Industry general manager Wang Jun as saying 71 miners were working underground at the time of the incident.
Wang confirmed the safety monitoring device of the coal mine stopped working when the gas blast happened.
Jingyuan Coal Industry Corporation is a state-owned coal producer with an annual capacity of 8 million tons.
On Saturday, 14 miners were killed by a coal mine blast in western China which injured six others.