HARBIN, Aug. 14 (Xinhua) -- Three people were killed and two seriously injured in an explosion at a chemical plant in northeast China's Heilongjiang Province on Monday, a press release from the China National Petroleum Corporation said.

A gas tank at the No.2 refining plant of the Daqing Refining & Chemical Company in Daqing, an oil city 160 km west of the provincial capital of Harbin, exploded at 6:16 p.m.

The explosion also caused a fire, which was put out at 8:11 p.m. The water polluted in the explosion was restricted in company's water treatment facilities, and there was no air pollution at the site, the press release said.

Witnesses said the explosion could be heard from "far away" and the company was enveloped in smoke

Rescuers found the bodies of the three victims including two drivers and a migrant rural worker, said the company's general manager Li Zhengguang.

The China National Petroleum Corporation has sent specialists to the explosion site to investigate the cause of the accident. Zeng Yukang, deputy general manager of the corporation, and local officials have gone to the plant, the press release said.

To eliminate nationwide oil shortage, China mobilized 40,000 workers and technicians and pooled 70,000 tons of equipment from 30 factories and mines to start up Daqing Oil Field in 1960.

Three years later, with an annual oil output of 60 million tons, Daqing successfully made China self-sufficient in oil.

Over the decades, more than 40 percent of the country's total oil output of 1.87 billion tons was produced from the largest oil production base in China. Enditem