A fire that started Monday afternoon in a centuries-old Biddeford apartment building was quickly extinguished by firefighters.

Capt. John Pothier said a swift response by Biddeford fire crews probably prevented the fire in a first-floor bathroom from spreading to the remaining three apartments inside the 2½-story wood-framed building at 38 South St.

Pothier said the cause of the fire remains under investigation, but does not appear to be suspicious. There are four occupied apartments and one apartment under construction. Everyone who lives in the building got out safely.

The building, which is located in Biddeford’s downtown, suffered minor damage. It was constructed in 1800, according to Pothier.