FAIRFIELD — An early-morning fire that spread from a barn storage area into an attached three-story apartment building left two families without their homes Sunday.

No one was hurt in the blaze at 16 Summit St., but a cat was killed in the fire, and the tenants of the two occupied apartments have been displaced, according to Fairfield fire Chief Travis Leary.

The structure fire was reported just before 3 a.m. Sunday. Firefighters from several departments were on the scene for nearly five hours.

Leary said the fire started in an attached barn storage area, then spread into the unoccupied third floor and attic of the apartment building. Flames and smoke were visible at the property before firefighters arrived, he added.

Firefighters knocked the fire down before it spread to the lower floors, and the tenants on the first and second floors escaped unharmed. The other apartments in the building were vacant.

“All the firefighters did an excellent job getting it knocked down quickly before it could spread,” Leary said.

Still, Leary said, the building could be a total loss because of sustained smoke and water damage throughout.

Two adults in the first-floor apartment and an adult and a child in the second-floor apartment were displaced by the fire and the resulting damage. Leary said the American Red Cross was helping those families to find temporary places to stay.

The chief said he did not think the tenants had renters insurance but that the building itself was covered by the landlord’s insurance.

Town of Fairfield assessing documents indicate the building — which was built in 1900 and has 18 rooms, including eight bedrooms — is owned by a limited liability corporation based in Waterville.

Firefighters from Albion, Clinton, Madison, Norridgewock, Oakland, Skowhegan, Waterville and Winslow joined the Fairfield department in fighting the fire. A crew from Delta Ambulance responded as well.

An investigator from the Office of the State Fire Marshal was at the site Sunday to try to determine a cause. Leary said the cause was still under investigation but initially appears to have been accidental.