The blast occurred at Yuanzigou Coal Mine in the Xiahua village of Hejin, where 20 people were cleaning up the flooded pit after a prior accident in June.

The ill-fated mine was flooded on June 24 – an accident that killed nine people but was covered up by its managers until the victims' families lodged a complaint with the local government, Xinhua reported.

Police have detained 11 people who have been held accountable for the disaster and its cover-up, including the mine owner.