The blast occurred on Sunday night at the Simachong coal mine in the city of Shaoyang, Hunan Province, an official from the county department told state news agency Xinhua.
Thirty-nine miners were working underground when the accident happened, the official said.
The 15 injured miners were rushed to a local hospital, where two remain in a critical condition.
Police have detained eight people believed to be responsible for the blast, including the mine's legal representative and managers, Xinhua reported.
A further investigation into the accident is underway.
Less than two weeks ago, at least nine people died when a coal mine in Shaodong Province flooded.
Local officials confirmed the mine was being operated illegally.
According to economic figures from the Chinese National Bureau of Statistics, last year’s coal mine death toll was down 33.75% on 2011, but the country’s safety record remained one of the worst in the world.
Government efforts to stamp out hazardous mines have resulted in the closure of more than 9000 small coal operations 2006.
Last September, Chinese authorities pledged to shut down 20,000 illegal and unsafe mines by 2015, following a string of deadly gas explosions and collapses.