Canada's TC Energy has shut the Keystone pipeline after one of the largest onshore spills saw 14,000 barrels leak into a Kansas creek

• TC Energy has shut the Keystone pipeline which ships crude from Alberta to the US.
• It halted operations after 14,000 barrels of crude oil spilled into a creek in Kansas.

Canada's TC Energy has shut the Keystone pipeline — which connects Alberta to the US — after 14,000 barrels of crude oil spilled into a creek in Kansas.

Pipe operator TC Energy announced the pipeline's shutdown at 5.35 a.m. CT on Thursday. The Canadian company said it initiated an energy shutdown and response at 8 p.m. CT on Wednesday after alarms went off detecting a pressure drop in the system.

The cause of the leak is not known. It is not immediately clear as of presstime when the pipeline is expected to come back online.

The affected segment of the Keystone pipeline system "has been isolated" and remains shut, the company said.

The leak at Keystone is the largest oil leak since a Tesoro Corp. pipeline leak in October 2013 that released more than 20,000 barrels of oil in North Dakota, Reuters reported, citing data from the US Pipeline and Hazardous Materials Safety Administration, or PHMSA.

It's the Keystone's seventh spill since starting operations in June 2010, Reuters reported, citing PHMSA data.

The PHMSA on Thursday said it's investigating the leak. It has ordered TC Energy to keep the pipeline shut until it authorizes a restart.

Leaks from Keystone are problematic because the pipeline carries tar sands and spills containing this substance are harder to clean up. Fears about such spills have already thwarted the Keystone XL oil pipeline extension projection, which President Joe Biden canceled in January 2021, even though the construction had already begun.

Keystone's shutdown sent US West Texas Intermediate futures soaring over 4% to top $75 a barrel on Thursday. But the strong gains did not hold — US crude futures were at $71.92 at 2.26 a.m. ET on Friday.

"Our primary focus right now is the health and safety of onsite staff and personnel, the surrounding community, and mitigating risk to the environment," said TC Energy in a public statement.

TC Energy did not immediately respond to Insider's request for comment sent outside regular business hours.