Four people were asphyxiated by methane gas in the cellar of a workshop used to ferment foods in northwest China's Gansu Province on Tuesday.

Four other workers and a policeman who came to help were also overcome but were later revived, an official said on Wednesday.

After the first victim was downed by the gas in the family-run workshop in Chengguan Town, seven others rushed to his aid only to be overcome, said the head of the general office of Hezheng county government Ma Zhancai.

Local police eventually retrieved everyone from the cellar but one of the policemen was also poisoned by the gas.

Four of the victims died on their way to hospital, while the other five are recovering, according to Ma.

An initial investigation has found that five of workers were local farmers who had no experience in the work they were doing.

The workshop has been closed by local authorities.

(Xinhua News Agency January 25, 2007)