A possible ammonia leak prompted police to evacuate Maple Lodge Farms in Brampton on Sunday morning.
Peel Regional Police said no injuries were reported but the building, located on Winston Churchill Boulevard near Steeles Avenue West, was evacuated as a result of the incident.
Police and Brampton Fire responded to the scene and advised anyone in buildings within a kilometre of the facility to stay inside.
It is not clear how the incident started or how it was reported, police said, adding that they have not yet confirmed that it is in fact an ammonia leak.
As of 2 p.m., emergency crews confirmed that the threat level had been reduced.
Police said everything else outside that closure can "resume as normal" and there is no threat to public safety.
Winston Churhill from Steeles Avenue to Embleton Road was closed but, it has since reopened.
