KUNMING - A gas explosion ripped through a coal mine in southwest China's Yunnan Province Thursday morning, leaving seven miners dead and 12 others injured, local authorities said.

The accident occurred at about 9:40 a.m. at a coal pit of Maanshan Coal Mine in Luxi County, the county publicity department said in a press release.

Twenty-nine miners were working underground at the time of the explosion. Ten managed to escape without injuries and 12 injured have been rescued and sent to the Luxi County People's Hospital.

The last seven were lifted to the ground at about 1:30 p.m and were found dead of suffocation.

Local work safety authorities are investigating the cause of the accident.