DAWU, Hubei -- About 20,000 residents in central China 's Hubei Province were evacuated after an ammonia leak at a nitrogenous fertilizer factory on Wednesday that has left one dead and six injured.

Special coverage: China-Africa Summit   Related readings: CNOOC chemical unit listed in HK Chemical leakage taints water supplies for 4,100 in E. China Water source out of danger in NW China city

The leak occurred around 7:50 a.m. in a nitrogen fertilizer factory in Dawu County when an ammonia pipe broke, said Chen Yixin, assistant general manager of the Huangmailing Phosphorus Chemical Industry Group Company, which owns the factory.

The leak was stopped at 8:40 a.m. after workers closed the valve of the pipe.