BISMARCK, N.D. (AP) — Federal regulators have ordered the Keystone pipeline to remain shut down until its Canadian owner takes corrective action aimed at determining the cause of a breach that leaked an estimated 383,000 gallons of oil in northeastern North Dakota.

The Pipeline and Hazardous Materials Safety Administration issued the order Tuesday to TC Energy. The action comes one week after the pipeline leak was discovered and affected about 22,500 square feet of land near Edinburg.

The order requires the company to send the affected portion of the pipe to an independent laboratory for testing.

TC Energy says it has about 200 people are at the site “focused on clean-up and remediation activities.”

Regulators say about 252,000 gallons of crude oil has been recovered.