GUIYANG, Aug. 1 (Xinhua) -- Four people were killed in a coal mine blast in southwest China's Guizhou Province, local authorities said Thursday.

The explosion happened at 4 p.m. Wednesday in a coal mine in Liangyan Town, the city of Bijie. Eight people were trapped when the gas explosion happened.

As of 8:30 a.m. Thursday, one person was saved, four killed and three remained trapped in the mine.

Rescue work is underway. The cause of the explosion is under investigation.