WESTBROOK, Maine — A fire that caused significant damage to a two-story apartment building in Westbrook early Tuesday morning has been ruled accidental, according to the Maine State Fire Marshal’s Office.

The Westbrook Fire Department responded to a reported structure fire at 23 Locust Street at approximately 2:46 a.m. on June 30.

When firefighters arrived, they encountered heavy flames extending up the left exterior side of the building. The fire had spread from the first floor to the second floor.

Due to the volume of fire, officials called for a second alarm, bringing mutual aid departments from surrounding communities to assist with suppression efforts.

All occupants safely evacuated the building. Four cats were inside at the time of the fire. Three escaped safely, while one died as a result of the fire and smoke.

No civilians or firefighters were injured.

The Maine State Fire Marshal’s Office responded to investigate the origin and cause of the fire. Following witness interviews, an examination of the scene and the fire investigation, officials determined that the fire began in an exterior trash can.

Investigators concluded that improperly discarded smoking materials caused the fire.

The apartment building sustained significant damage and has been deemed uninhabitable.