The death toll in Saturday's chemical plant explosion in north China's Shanxi Province climbed to four Sunday, after rescuers found the body of a missing worker, the emergency rescue headquarters 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, one was missing and two were seriously injured.

Another 37 workers were hospitalized with slight injuries, of whom 34 were wounded by broken window panes.

As of midday Sunday, most of the injured workers had been discharged from hospital.

Rescuers worked all night Saturday to put out fire and search for more victims. The flames were extinguished Sunday morning.

A local publicity official said no pollution had been observed in the factory area and neighboring villages.

"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.