Crude oil erupting from a leak in a petroleum pipeline early Wednesday morning in Yan'an, Northwest China's Shaanxi Province, has caused serious pollution and US$480,000 in economic losses, officials say.

　　The incident was believed to be caused by thieves attempting to highjack oil from the line, but local police said it is too early to make a final conclusion. An investigation is on-going.

　　After the incident, local government officials organized police, firefighters, technicians and soldiers to help quell the leak and control pollution of farmland in the area, said Hao Baocang, Yan'an vice-mayor.

　　"We assembled oil trucks and organized soldiers and local residents to help recover the leaking oil," Hao said.

　　The pipeline puncture was finally plugged about 12 hours after the incident occurred about 1 am on Wednesday. Some 1,000 tons of crude oil spewed out 2 hectares of farmland in the incident, causing serious environmental pollution, according to Lei Da, deputy director of the Yan'an Supervisory Bureau of Production Safety.

　　According to Li Mo, Changqing Oilfield manager in charge of the pipeline, a monitoring system revealed pipeline pressure had been reduced, indicating that crude oil was leaking. Workers switched two oil pumps off at the upper and lower ends of the line at about 4 am.

　　Li and his colleagues went to the leak site and found tools believed to have been left behind by thieves.

　　"The leak caused at least 4 million yuan (US$480,000) in economic losses," Li said.

　　Worse, the nearby farmland was contaminated and trees and grass were damaged. The irrigation canals were polluted. The aftermath of the serious pollution is not easy to be tackled, said Han Chang'an, director of the Yan'an Environment Protection Bureau.