According to the State Administration of Work Safety (SAWS), six workers remained missing after the explosion which occured at the state-owned Da Yangquan coal mine in Shanxi province.
Hopes of finding the six alive are remote because they are trapped in tunnels now blocked by rubble.
Gas explosions are common and often fatal at coal mines in China, despite increased efforts to improve work safety in recent years. Newspaper China Daily reported statistics which show that 53,302 people died in 44,723 accidents, including coal mine accidents, during the first half of the year.