The accident took place at around 1 p.m. on Sunday at Guanyin Coal Mine of Anping Township, Lianyuan City, when 48 miners were working in the shaft and 33 managed to escape, said Yan Yinchu, deputy director of the Provincial Coal Mine Safety Supervision Bureau.

Six miners were confirmed dead in the accident and three others were rescued and are receiving treatment in a local hospital, including one with serious gas poisoning. The injured people have no life of danger, doctors said.

But the six missing miners have little chance of survival, rescuers said, adding that the complicated condition underground and excess amount of gas had delayed the rescue work.

The mine boss and a few managers fled after the collapse happened, Yan told Xinhua.

He said they are trying increasing ventilation and other ways to lower the density of gas.

Guanyin Coal Mine is a township-administered coalmining venture capable of producing 30,000 tons of coal annually, but the mine's work safety license had been revoked before the accident and it has been ordered to suspend production, local authorities said.