The Keystone Pipeline was shut down Wednesday night after a leak was detected near the Nebraska-Kansas border.

“We have shut down the Keystone Pipeline System and mobilized people and equipment in response to a confirmed release of oil into a creek in Washington County, Kan., approximately 20 miles (32 kilometers) south of Steele City, Neb.,” Calgary-based TC Energy said in a statement.

The pipeline, a key conduit for Canadian oil to the U.S., was shut down around 8 p.m. local time on Wednesday night after alarms were triggered following the detection of a pressure drop in its systems.

The pipeline can transport around 610,000 barrels of oil per day to major refineries across the U.S.

“The affected segment has been isolated, and booms deployed to control downstream migration of the release,” the company said. “The system remains shutdown as our crews actively respond and work to contain and recover the oil.”

The company did not say anything about the amount of oil spilled or the timing of when the pipeline might become operational again.

U.S. crude oil prices jumped as much as two percent following the news. They have since declined again to be unchanged for the day.

The cause of the leak has not been determined.

The shutdown Keystone Pipeline is separate from the Keystone XL pipeline project Joe Biden halted in one of his first actions as President of the United States.