TC Energy Corp. says it has shut down the Keystone pipeline while it investigates a potential oil spill in North Dakota.

In a brief statement on Wednesday, the Calgary-based company says it is investigating a possible incident after detecting a drop in pressure near its facilities at Edinberg, N.D., at about 9:20 p.m. MT on Tuesday.

It says Keystone customers have been notified the pipeline will remain shut down while it investigates the incident.

According to The Associated Press, some wetlands appear to have been affected by the oil leak, but not any sources of drinking water.

There are no estimates of volume or how much land may have been affected.

A segment of the pipeline in Missouri was shut down in early February for nearly two weeks after a leak of about a dozen barrels of oil was discovered.