BISMARCK, N.D. (AP) — 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. and potentially leading to higher gasoline prices.

South Bow, a liquid pipeline business that manages the pipeline, said it shut down the pipeline after control center leak detection systems detected a pressure drop in the system. The company estimated that 3,500 barrels of oil were released and said the spill was confined to an agricultural field in a rural area, about 60 miles southwest of Fargo.

“The affected segment has been isolated, and operations and containment resources have been mobilized to site,” the company said. “Our primary focus right now is the safety of onsite personnel and mitigating risk to the environment.”

The pipeline transported an average 624,000 barrels — or more than 26 million gallons — per day in 2024, according to Canadian regulators. It stretches 2,689 miles from Alberta, Canada, to Texas.

The pipeline’s shutdown could quickly lead to higher gasoline prices in the Midwest, said Ramanan Krishnamoorti, vice president for energy and innovation at the University of Houston.

It could raise prices at the pump within one or two days, but will have a greater impact on diesel and jet fuel, Krishnamoorti said. The Keystone pipeline transports a large amount of a unique, heavy crude that only is available from limited sources, he said.

Higher diesel costs could lead to grocery price increases because diesel trucks transport those products, he said.