BISMARCK — The operator of a portion of the Keystone pipeline that runs through North Dakota estimates about 3,500 barrels, or 147,000 gallons, of crude oil spilled into a field near Fort Ransom Tuesday, April 8, after a pipeline malfunction.

Trucks and workers started a cleanup effort at the site of a spill of the Keystone oil pipeline in rural North Dakota

FORT RANSOM, N.D. — The Keystone Pipeline has spilled oil into a field near Fort Ransom. The amount of crude oil that may have spilled has not yet been determined. Bill Suess, spill investigation program manager with the North Dakota Department of Environmental Quality, said it is not yet clear whether the pipeline ruptured or sprang a leak.