Sirens sounded and a Chemical Valley alert was issued Friday morning at Arlanxeo.
A hexane leak at the Vidal Street South plant was reported through the Aamjiwnaang Notification System.
A message from the company recorded on the Community Awareness and Emergency Response Line just before 10 a.m. said, "Arlanxeo emergency personnel are currently addressing a minor leak at the butyl unit, the Sarnia fire department has been notified."
An all-clear was issued before 10:30 a.m.
Arlanxeo started a planned six-week shutdown of the butyl unit Wednesday night.