Firefighters work at the scene of a fire in South Williamsport on Tuesday night. PHILIP HOLMES/Sun-Gazette

A fire that ripped through the vacant former Merrick Brothers dealership at 1530 W. Southern Ave. in South Williamsport on Tuesday night was intentionally set, according to borough Fire Chief Jeff Trammell.

He said Cpl. Nathan Birth, a state police fire marshal, investigated the cause of the fire and determined it was arson.

Flames were visible from the building when borough firefighters arrived on the scene There were no reports of injuries.

The building, owned by Hutchinson Companies, of Williamsport, has been vacant for several years, according to officials at the scene. Damage was estimated at least $50,000, Trammell said.

It took about 20 minutes for firefighters to get the fire under control. Trammell said firefighters discovered a burned up mattress inside the building, leaving investigators to believe that a homeless person possibly occupied the structure.

In addition to borough firefighters, crews from several other communities responded, including Williamsport Bureau of Fire, Loyalsock Township, DuBoistown, Old Lycoming Township, Montoursville and Jersey Shore.

Volunteer fire police shut down a section of West Southern Avenue, detouring traffic away from the fire for about an hour.