Pipes for the Keystone XL pipeline stacked in a yard near Oyen, Alberta. (Jason Franson/Bloomberg)

South Bow Corp.’s Keystone oil pipeline has been shut after a spill in southeast North Dakota, according to an official with the state Department of Environmental Quality.

The pipeline, which carries crude from Canada as far south as the U.S. Gulf Coast, was shut by a worker at a pump station after the spill was discovered at 7:44 a.m. local time, Bill Suess said by phone. Oil has been found covering an agricultural field near the pump station. The worker heard a loud bang at the time of the spill and shut the line in two minutes, he said.

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South Bow didn’t immediately respond to a request for comment.