Sporadic flames were still burning Sunday morning at a chemical plant in north China's Shanxi Province where an explosion killed three workers and injured dozens Saturday night, local officials said.

The blast happened at 7:10 p.m. Saturday at Yushe Chemical Industry Co. Ltd. in Yushe County of Jinzhong City. Three workers died at the scene and two were seriously injured, the local government said in a press release.

Another 37 workers were hospitalized with slight injuries, it said.

The blast broke almost all the window panes in buildings within 100 meters from the site. At least five fire engines were mobilized to put out the flames that engulfed several workshops.

A local publicity official said no pollution had been observed.

"The provincial environment bureau has found no harmful substance in the air and the factory has not discharged any waste water after the blast," said Wang Hongchang, publicity official at the Yushe county committee of the Chinese Communist Party, at a press conference early Sunday.

The cause of the accident is still under investigation.

Yushe Chemical Industry Co. Ltd., with 2,700 employees, produces PVC, sodium hydroxide and other chemicals.