LOWELL – A Level 6 fire ravaged a Centralville apartment building Thursday, leaving 22 residents homeless and sending four firefighters and one resident to the hospital, all in non-life-threatening conditions.

The cause of the fire at 73 Aiken Avenue, which was first reported to firefighters around 11:30 a.m., is currently under investigation.

The fire was under control about an hour and a half after the first emergency call. As firefighters cleaned up the charred three-story building, Lowell Fire Chief Phil Charron told reporters at the scene that he could not say for sure if the building was a total loss, but added, “If I were to bet…”, suggesting that the building had been destroyed.

Further devastation may have been prevented by Frank King and his 25-year-old son, Austin King. The couple, who work at DeRosa Properties on Farmland Road, saw the smoke a few blocks away and went to investigate. Frank King said they stopped and saw “thick black smoke” pouring out of a ground-floor apartment on the front right side of the building when facing the building.

“I guess we heard a window break because of the heat and the flames went really high,” Frank King said. “It was a fire.”

At that point, firefighters were not on the scene. Frank King said there were people outside the building filming the burgeoning flames. He asked them if anyone was inside, but they weren’t sure. Frank King said he was concerned and went into the building with his son to make sure everyone was out.

Frank King said he visited the apartments on the first and second floors and found people there who had no knowledge of the fire in the building. Austin King, meanwhile, helped an elderly woman out of an apartment in the rear.

“I didn’t go too far because the smoke and heat in that hallway was insane,” Frank King said. “As soon as I kicked the door open, you could feel a temperature change.”

His video shows bright orange flames engulfing the building and black smoke rising from it as firefighters arrive on the scene.

Land records show that the wooden building, constructed in 1890, has 25 rooms. According to Charron, the building consists of six separate units.

The fire chief explained that the fire was extinguished six times in order to mobilize the necessary forces to contain the flames. He estimated that about 55 to 60 firefighters were deployed at the scene.

Due to the extreme conditions, firefighters who were conducting an interior attack on the flames had to evacuate the building.

“There was a very intense fire in the attic,” Charron said. “The firefighters had to evacuate as the fire spread. They had to get out pretty quickly.”

According to Charron, one firefighter had to jump out the window while others took the stairs.

A total of eleven firefighters were examined on site by the emergency services, four were taken to hospital. In addition, one resident of the building was taken to hospital due to smoke inhalation.

Jordyn Hoar, a Bridge Street resident, said from the scene of the fire that she knew the woman who was hospitalized. Hoar said the woman lives in the first-floor apartment on the front right side of the building with her husband and four children, who were at school at the time of the fire.

Hoar said she was told the woman and her husband heard an alarm in the apartment and when they opened the bedroom door they saw a wall of flames in front of them.

According to Hoar, two puppies that lived in the apartment were killed in the fire.

Hoar said when she heard about the fire, she immediately rushed to check on the family and was shocked by the extent of the damage.

“It was a crazy scene,” Hoar said. “I don’t think I’ll ever forget it.”

Charron praised firefighters for their “excellent work” and thanked emergency agencies. He said firefighters had traveled from as far away as Nashua, New Hampshire and Burlington to help.

The Red Cross was called to assist the homeless, and the Salvation Army Emergency Disaster Canteen of Lowell was also on site, providing food, drinks and emotional support.

“The Salvation Army’s EDS is working with disaster response partners to assess current needs of survivors and is available to provide emotional and spiritual care to first responders and displaced residents,” it said in a statement released Thursday. “The Salvation Army’s Lowell Corps and Community Center is also prepared to assist displaced residents with future needs, including social services, and will work with partner organizations.”

Follow Aaron Curtis on X, formerly known as Twitter, @aselahcurtis