Four miners have been found dead and four others remained missing more than two days after a coal mine flooding in southwest China, local authorities said Friday.

Rescuers were pumping out water and clearing sludge to reach the missing workers of a coal mine at the border of Dushan County in Guizhou and Nandan County in Guangxi Zhuang Autonomous Region, the Dushan county government said in a press release.

The rescue operation, however, was complicated by the high density of gas and narrow shafts.

Police have arrested four owners of the illegally-operating mine.

In another accident, rescuers have found three bodies in a flooded coal mine in Guiyang, the capital city of Guizhou.

Nearly 300 rescuers were still working to relocate the other nine workers who have been trapped for more than five days.