An explosion at a chemical plant in eastern China killed at least 16 people Friday and prompted the evacuation of 7,000 others, state media and officials said.

Also Friday, two unrelated explosions at another chemical plant and aboard an oil tanker injured at least five people, with two others missing and feared dead.

The 9 a.m. explosion at the Fudu Chemical Plant in Jiangsu province's Linhai Township, about 190 miles north of Shanghai, shattered the facility.

A spokesman for the surrounding Sheyang county government initially put the death toll at 12, but the official Xinhua News Agency said Saturday that the figure had increased to 16. The agency also said the injury toll was raised from about 12 to 29 with three people missing.

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The cause of the 9 a.m. blast is still under investigation, said the spokesman, who like many Chinese bureaucrats would only give his surname, Huang.

The news agency reported Saturday that the blast was caused by "improper operations by workers" but did not elaborate.

Fudu is a major producer of fluorochemicals for industry, according to the company Web site. newspaper reports said the company had been cited for violating pollution standards in the past but there was no mention of safety problems.

Reached by phone, Fudu General Manager Xue Chunlin said it was "not convenient" for him to comment on the cause of the accident or condition of those injured.

Though no dangerous levels of pollution have been detected, authorities evacuated 7,000 people from about a mile around the blast site as a precaution, he said. Xinhua said the evacuees were later allowed to return to their homes.

One hour before the blast, an explosion and fire struck a plant belonging to the Shanghai Yuanda Peroxide Co. Ltd., seriously injuring at least four people and billowing thick smoke across the Baoshan industrial district to the city's north, the official Xinhua News Agency said.

The fire was quickly brought under control and investigators were looking into the cause, said a woman who answered the phone at Yuanda's headquarters in Shanghai.

In a later report, Xinhua said the Yuanda explosion had initially been ruled an accident with no sign of foul play.

Yuanda's Web site describes it as a joint venture with a Hong Kong company that produces 50,000 tons per year of the chemical peroxide.

Shortly before the Yuanda accident, a massive explosion split the hull of an oil tanker sailing down a canal in central Jiangsu's Yizheng district, Xinhua reported.

Two people aboard the boat were reported missing after the blast and feared dead, the report said. Another person was taken to a hospital in critical condition, it said.

Factory accidents in China kill thousands each year in fires, explosions and other incidents, most often blamed on insufficient safety equipment and workers ignoring safety guidelines. The resulting contamination of air and water has also forced the shutdown of drinking water systems to entire cities, inflicting massive financial losses.