Ten other workers in the immediate area of the blast at the 5 million tonne capacity Sijiazhuang mine escaped unharmed.
China and human rights-focused newspaper The Epoch Times said nearly 900 miners were working underground at the time of the explosion.
According to official state media agency Xinhua, six officials have been implicated in an investigation into the incident.
Sijiazhuang’s board chairman and general manager, chief engineer, work safety director, ventilation director and the mine’s Communist Party committee chief were reportedly dismissed.
The chief engineer of the Jindong Coal Mine Management Company, which administers Sijiazhuang, was also dismissed.