A fire that destroyed two homes in Mill Woods on Sunday was started by a discarded cigarette butt.

Fire investigators have determined that the butt smouldered in the soil and ignited a plastic planter on the back deck of a house at 20th Street and 27A Avenue.

The fire then spread up the vinyl siding and into the attic of the house.

Two homes were destroyed and the siding was melted off two others.

Damages are estimated at $1 million.