Blasts hit two oil pipelines in Dalian, a port city in northeast China's Liaoning Province, Friday.
An explosion first hit a 0.9 meter-diameter oil pipeline at about 6 p.m. and triggered an adjacent smaller pipeline to explode near Dalian Xingang Harbor.
Both pipelines, owned by China National Petroleum Corp.(CNPC), caught fire and more than 400 firefighters and 110 fire engines are working at the site.
Blaze of the larger pipeline has been extinguished by 11:30 p.m. but more than 200 meters of the smaller one is still on fire as firefighters failed to turn off its oil pump.
The government is sending special jets to transport fire foam for the campaign.
An oil tank that was unloading oil in the harbor when the blast broke out had left the scene unharmed.
The pipelines were links between oil ships and land tankers.
Local authorities are investigating the incident.