BANGOR — A fire that gutted a garage on Hancock Street and melted siding and broke windows on three nearby apartment buildings Friday afternoon is under investigation by the Bangor Fire Department, the Bangor Police Department and the state fire marshal’s office.

Bangor Assistant Fire Chief Rick Cheverie said that the fire near the corner of Hancock and Newbury streets was reported about 2 p.m. by an Etna firefighter, who spotted it while driving by.

Firefighters, who were still at the scene around 8 p.m. Friday, will remain there overnight to watch for flare ups, Cheverie said.

Despite initial reports that a man was inside the garage when it caught fire, Cheverie said Friday night that this proved not to be the case.

Several propane tanks, some in the garage and two attached to nearby apartment buildings, were also a concern. Despite the heat, however, no explosions occurred, Cheverie said.

Bangor police Sgt. Dave Bushey confirmed Friday night that the police are seeking a person of interest in connection with the fire. No other details were released Friday evening because the fire is still under investigation.

Cheverie said what remains of the three-bay garage, the back section of which is supported by posts leading to a roughly 5-foot drop to the nearby railroad tracks, was too unstable Friday night for investigators to enter. Also complicating matters is that part of the garage was two stories tall and sections were in various stages of collapse.

The garage is located next to an apartment building at 345 Hancock St. owned by Sid Smith, who is believed to be in his late 80s and does not reside on the premises, Cheverie said. He said Smith also owns an adjacent apartment building at 349 Hancock St. He said the buildings are managed by an individual from Texas, who has a local employee.

Vinyl siding on those two buildings — along with a third apartment building at 339 Hancock St. — were melted by the heat from the fire, which also caused several windows to break, Cheverie said. He estimated damage to the three buildings at between $75,000 and $100,000.

All three structures were deemed habitable despite the exterior damage.

A thick, billowing cloud of smoke could be seen over the Penobscot River as the fire raged Friday afternoon. Firefighters were on the scene within four minutes of the alarm going off, Cheverie said.

The assistant fire chief noted the garage was fully engulfed in flames when crews arrived, and it took firefighters an hour to knock the fire down.

Jean Severance, who lives in the next house down the street, had two cars in the garage when the fire broke out.

Severance said she told her son to get the cars out, which he managed to do, but a snowblower could not be salvaged from the three-car garage.

Hancock Street initially was shut down to traffic from Newbury to Birch streets while crews battled the blaze. One lane of traffic from State Street to Newbury street was reopened Friday evening.

“At this point we can’t rule anything out,” Cheverie said. He noted, however, that the garage did not have electricity and that there was no lightning Friday.