Warrnambool police interviewed a Koroit woman aged in her 40s last night and she is expected to be charged with criminal damage by arson.

Police inquiries are continuing and the woman may also face other charges relating to starting a fire on a day of total fire ban.

A quick thinking chef helped avert major damage when he used a kitchen fire extinguisher to put out the fire and stopped it burning a disused shed.

The alarm was raised soon after 4pm yesterday.