About 20 tonnes of toxic hydrofluoric acid leaked from a chemical company in east China's Zhejiang Province, local government authorities said Thursday.

The incident occurred at around 2:30 p.m. at the factory compound of the Zhejiang Hailan Chemical Co., Ltd. located in the High-tech Development Zone in Quzhou City.

Company workers and nearby residents have been ordered to evacuate, and no casualties have been reported, according to fire authorities.

Local police, fire fighters and environmental protection personnel have rushed to the site to control and clean up the leak. The cause of the leakage has not been found yet.

Hydrogen fluoride is a chemical compound used mainly for industrial purposes, such as etching glass, and is extremely corrosive. Inhaling the hydrofluoric acid gas can cause severe health damage and even death.