CHANGSHA - Seven people were killed and one injured in a coal mine explosion in Central China's Hunan province Thursday evening, local work safety authorities said Friday.

The explosion occurred at about 7 pm Thursday at the Qiyi Coal Mine in the city of Changning, the provincial coal mine safety bureau said in a press release.

Explosives set off by workers to excavate mine shafts triggered explosion of high levels of gas in wake of bad ventilation, the initial investigation showed.

The mine is under technological renovation to expand annual output to 60,000 tonnes.