AMHERST — A Sunday afternoon fire at a four-story, nine-unit apartment building in downtown has displaced at least 24 residents, mostly college students, and closed a few businesses.

The Amherst Fire Department received a 911 call at 4:11 p.m. from a resident at 69 South Pleasant St. about a fire on the rear fourth-floor porch of the building, which led to a box alarm being sounded for all on- and off-duty Amherst firefighters, according to Amherst Fire Chief Lindsay Stromgren.

Crews that arrived on the scene to the Bank Block, as it has commonly been called since its construction in 1881, found heavy smoke coming from that rear fourth-floor balcony, with the fire spreading quickly to the third-floor porch due to the building’s older construction, Stromgren said. The fire then moved up to a void space below the roof, and horizontally across and into the back of the building.

Crews on scene, with a second alarm sounding, worked to extinguish the fire from the inside, and a ladder truck was used to put out the fire on the porches, and to access the roof to extinguish the fire there. The fire was under control within about two hours, with crews remaining on scene to put out hot spots until 9 p.m., Stromgren said.

Most of the damage was confined to the wooden balconies and a back staircase that provides a second egress, and to the roof, Stromgren said. The extent of the damage isn’t yet fully known, he said.

Nearly all residents were home at the time of the fire, but got out safely.

Hayden August was visiting his younger sister, a University of Massachusetts senior who lives in one of the apartments and had just returned from having graduation photographs taken. August said the burning smell was noticeable upon getting back.

“We went to her apartment on the top floor and were sitting at her kitchen table when we heard someone in the hallway bang on the door and yell ‘fire.’” August said “She stuck her head out the door to see what was going on and another resident of the building was there, who confirmed that the back porch was on fire.”

The alarm then sounded.

Electricity and gas were both shut off to the building during the fire, though electricity was later restored for the businesses. The building is considered uninhabitable, though residents were allowed back in to get belongings.

The American Red Cross was on scene to assist residents with finding housing for the evening. Four of the tenants are Amherst College students, and the college is helping them get new accommodations, while 20 are UMass students, with the university assisting them. There are one or two non students who also live in the building, Stromgren said.

The businesses in the building, which sold to Lincoln Real Estate in March, include La Veracruzana restaurant, Laughing Dog Bicycles and a lawyer’s office. For many years, the street level space also was where Collective Copies, Off the Common Bookshop and Levellers Press operated from in Amherst. Stromgren said the hope is to have the fire alarm system reset so the businesses can reopen.

Philip Pallante, the property manager for La Veracruzana, said the restaurant didn’t sustain any damage from the fire or the response, but did lose power, which was restored in time so the food stored in the cooler was unaffected. Patrons and employees, though, did evacuate the restaurant, which was closed Monday, as well.

The process of having the restaurant reinspected is complete, with the waiting for the fire alarm system to be operational.

“We’re just hoping we can get it going sooner rather than later,” Pallante said, pointing out spring is a busy time with graduations coming and many people visiting town.

La Veracruzana, which also has locations in Northampton and Easthampton, has been in Amherst since the early 1990s. Last fall, the restaurant was closed for several days after a concrete truck arriving to the neighboring five-story mixed-use building under construction hit the Bank Block building, damaging equipment.

The Amherst building and electrical inspectors were on scene Sunday and continued to work with the building and business owners.

Due to the age of the building, Stromgren said sprinklers were not required throughout, with a rudimentary sprinkler system in the common areas that did little to combat the fire.

Amherst firefighters were assisted by Belchertown Fire, Hadley Fire and Northampton Fire personnel, and a Granby Fire ambulance, and the Pelham Fire Department provided station coverage at the Central Fire Station. A firefighter Rehab unit was also on scene staffed by the Massachusetts Department of Fire Services. There were no injuries to any personnel.

During the fire, South Pleasant Street between Amity Street and Northampton Road was closed to traffic, necessary for laying out of hoses, while many people gathered on the North Common in front of Town Hall to observe the incident.

The cause of the fire is being investigated by the Amherst Fire and Police Departments, and the State Fire Marshal’s office. Stromgren said the belief is that the fire started on the fourth-floor porch.

That is the same location where a fire broke out last July. That fire was brought under control a short time later, even with limited staffing, but this time the fire got more of a head start. Stromgren said the porches, or balconies, often in urban settings, can pose fire risk to buildings that are otherwise masonry structures.

Scott Merzbach can be reached at smerzbach@gazettenet.com