LISBON — The cause of a smokey house fire at 12 Houston St., Lisbon Falls on Sunday morning remains under investigation, Lisbon fire Chief P. Sean Galipeau said.

Two representatives from the State Fire Marshal’s office were at the scene Sunday afternoon with Galipeau in an effort to determine a cause. Damage was estimated at about $100,000.

The fire, which was called in at 8:22 a.m., started in a back bedroom which was heavily damaged, Galipeau said, while the remaining portion of the house sustained “major smoke damage.”

Firemen had the blaze knocked down by 8:31 a.m. The house is owned by Sherry and Michael Hersom. Michael Hersom was at home at the time of the fire and escaped unharmed. The Red Cross was at the scene to provide assistance.