KUNMING, Aug. 5 (Xinhua) -- An estimated eight people have been trapped underground after a gas blast hit an illegal colliery in southwest China's Yunnan Province on Monday afternoon, local authorities said.

The blast happened at 3:40 p.m. at the coal mine in Qingmen Village, Zhaoyang District of Zhaotong City, said the district authorities.

Rescue work is under way.