A chemical plant in central China's Henan Province is ablaze after it exploded early Wednesday, July 15, 2009. [Photobase.cn]

Rescuers have found the bodies of two workers who disappeared after a chemical plant explosion in central China's Henan Province early Wednesday, bringing the death toll to seven, said a local official.

Declaring an end of the rescue operation late Wednesday, Liu Shangjin, acting mayor of Yanshi, a county-level city in Henan, who headed the rescue operation, ordered further investigations into the incident, including the cause of the blast, and calculation of property damage.

The blast occurred at Luoran Co. Ltd in Yanshi at 2 a.m. while 17 people were working the night shift. Five bodies were found in the immediate aftermath and nine people were seriously injured. Two more were missing, and one worker escaped unhurt, said a rescue headquarters official.

The official said a fire in a warehouse had caused the explosion of about 10 tonnes of chlorobenzene, a flammable intermediate for making other chemicals.

The factory was engulfed in flames and fire-fighters only succeeded in extinguishing the blaze at midday.

Rescuers said they found the location of the two missing workers in the debris around midday, and life detectors showed that at least one was still alive.

"But the pungent, toxic air following the explosion hindered the speed of the rescue operation, so when we eventually reached them, they were already dead," said one rescuer. Some rescuers complained of chest pains, and red and watering eyes.

Local environmental protection departments said they had sealed the discharge pipe at the chemical plant and had been closely monitoring the quality of the air around the area.

Tests showed that the explosion caused no pollution to local rivers and groundwater, said an environmental protection department official.

Several hundred residents who lived within a radius of 1,000 meters of the factory were evacuated shortly after the explosion. A total of 108 residents near the factory were injured, mostly by flying glass, said the rescue official.

All the injured were taken to hospital.

Luoran Co. Ltd, which employs 180 people, produces chemicals for the dyeing industry. Its products are also exported to Japan, Britain and several southeast Asian countries.