Canadian operator Enbridge shut down one of its pipelines after a leak at the Regina Terminal in Saskatchewan.
A release from the line within the on-site pumping station had been reported.
A spokesman said there was no impact to the public, wildlife or waterways following the incident.
He said: “Enbridge first responders with clean-up and response equipment are on-site and expect the cleanup of free product to be completed tomorrow.
“Immediately upon Enbridge’s confirmation of the release, the pipeline and pumping station were shut down.
“Assessments have confirmed that the release occurred entirely within the facility, and that all product is contained on-site in designated catchment areas.
“All regulatory, municipal and provincial officials have been notified.”
The initial estimates of the release were around 1,350 barrels.
An investigation has been launched into the incident.