JOIN USThe accident occurred last night at Yuanyang Colliery in the city of Anshun where a total of 31 miners were working.
Rescuers have confirmed that 10 people had escaped either by themselves or with their help.
The bodies of other 21 miners were recovered by the rescue teams in the mine which was struck by the burst of poisonous carbon monoxide, Xinhua news agency reported.
"We arrived at the mine to carry out the rescue at midnight, and helped bring three of the survivors out of the shaft," said a rescuer surnamed Zhao.
He said five of the 10 survivors were in hospital after being poisoned by carbon monoxide from the coal-gas outburst.
Wang Shuhe, deputy director of the State Administration of Coal Mine Safety, is on the way to the accident site. Yuanyang Colliery is a private mine that was being upgraded at the time of the accident.
Mine accidents have become very common in energy hungry China as safety concerns were widely ignored in the rush to meet the surging demand for coal, source of about 70 per cent of the country's energy.
More than 2,600 miners have been killed in China last year, according to government figures.
Last month a flood at the vast, unfinished Wangjialing mine in the northern province of Shanxi left 153 workers trapped underground, but more than 100 were rescued.