Firefighters were called to a residence on Stuart Street at around midnight Wednesday night for the smell of smoke.
Sarnia Fire and Rescue arrived on scene to discover a basement fire in the duplex.
According to a social media post, the blaze was quickly extinguished.
Public Education Officer Mike Otis said the cause of the fire is being investigated but at this time, it's not believed to be suspicious. A Sarnia Fire investor was still at the scene Thursday afternoon.
A damage estimate has not been established yet.
No injuries were reported.