Six maintenance workers got poisoned in a gas leakage accident while repairing underground gas pipelines in east China's Zhejiang Province, a local gas company source said on Thursday.

Four of them were in a coma, including one in critical condition, said the source with the Hangzhou Gas Co., Ltd.

The six workers were making repairs at an underground gas pipe site in downtown Hangzhou, the provincial capital, at around 2 PM Thursday, when gas leaked out from a gas pipe valve. Two workers fell into a coma at the scene inside a well.

Other workers on the ground went down into the well to rescue their co-workers, but were soon poisoned one after another and only one of them managed to escape, said the company.

Firefighters carried the workers to the ground. And four in a coma were immediately sent to a local hospital.

The leaking valve was closed by emergency workers. Fire fighters used water to dilute gas in the air to prevent an explosion.

The cause of the accident is being investigated.

(Xinhua News Agency June 23, 2006)