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.

An estimated 3,500 barrels of oil spilled in a field near Fort Ransom, N.D., and the release was contained, the pipeline’s operator said.

The nearly 2,700-mile Keystone oil pipeline was shut down Tuesday morning after it ruptured in North Dakota, halting the flow of millions of gallons of crude oil from Canada to refineries in the U.S.