BERWICK (AP) — Firefighters said a 6-unit apartment complex in the town of Berwick has been destroyed in a fire that is believed to have started after inflammable material was left too close to an electric heater.

Berwick Assistant Fire Chief said Bruce Plante says the fire started in a second-story unit on Old Pine Hill Road South at about 11:40 p.m. Friday.

No residents were hurt, but Plante said a firefighter fell about 20 feet when an exterior staircase collapsed. The firefighter was bruised, but did not break any bones.

The Red Cross is helping nine or 10 people who were displaced by the fire.

Firefighters said the building was destroyed.

Plante told the Portland Press Herald six fire departments helped fight the blaze.