More than 30 people suffered chlorine gas poisoning after the toxic gas leaked out from a plant Tuesday in east China's Jiangsu Province, local authorities said.

The gas leaked out of Dahe Chlor-Alkli Co., Ltd. in the morning and poisoned employees of Zhijiang Chemicals Co., Ltd. who were downwind in an industrial park of Xiangshui County, Yancheng City, according to a statement from the municipal government.

Those poisoned were immediately rushed to a local hospital. Some were subsequently discharged but 21 people were still being treated. No deaths were reported, according to the statement.

A worker of Dahe Chlor-Alkli Co., Ltd. mishandled a valve which caused the accident. The leak lasted about five minutes, the statement said.

Local authorities were working to evaluate and contain the accident's impact on the environment, it said.