URUMQI -- Four people were confirmed dead in a coal mine accident Thursday in northwest China's Xinjiang Uygur Autonomous Region, the local government said Friday.

The accident occurred at 8 p.m. at Changsheng Coal Mine in Shache County of Kashi Prefecture.

Investigators said the miners were suffocated by carbon dioxide because the miners opened an obturated room while working in the tunnels.

Rescue work and efforts dealing with the aftermath of the accident are going on. The cause of the accident is under further investigation.