Shell Canada reported the release of hydrocarbon Thursday morning at its Corunna manufacturing site.
It happened at about 8:30 am, according to a post to the Sarnia-Lambton Alerts system.
Shell said an emergency alarm was sounded and its emergency operations center activated.
“The release has been contained at the unit,” the company said. “External air monitoring has been put in place with readings showing no offsite release.
Shell said the province’s Spills Action Center was notified.
The Shell Manufacturing Centre, next to the St. Clair River between Corunna and Sarnia, produces gasoline, distillates, liquid petroleum gas, heavy oils, pure chemicals and solvents, the company’s website says.