Suncor is investigating after a spill at its Sarnia refinery early Sunday morning.
The company said the incident happened at its dock facility on the St. Clair River.
In a notice sent out through Sarnia-Lambton alerts, Suncor said a small amount of hydrocarbon was released during a loading operation which it was able to contain.
Residents may have noticed increased activity around the docks Sunday as a result.
"Our first priority is always for the safety of our employees, community members, and the environment," read the notification.
The company said the appropriate parties were notified of the incident.