A five-alarm fire that ripped through three multifamily houses in the Lower Belvidere neighborhood yesterday afternoon appears to have been started by children playing with a lighter.

Fire Chief Edward Pitta said last night investigators believe the fire was sparked when children were playing with a lighter in an alley behind a vacant home at 90 Chestnut St. and a triple-decker home at 19-21 Willow St.

The fire spread across those houses to a third multifamily house at 84-86 Chestnut St., creating a billow of smoke that could be seen miles away.

The American Red Cross assisted 28 residents who were displaced by the fire who lived within nine units in the three homes, spokeswoman Kat Powers said.

The fire, which broke out about 3:30 p.m., was contained a little after 5 p.m. Deputy Fire Chief Patrick McCabe said at the scene.

The blaze appeared suspicious, and officers from the Police Department's Criminal Investigations Division were on the scene.

There were no reported injuries, fire officials said. However, one firefighter sought medical attention from paramedics and was carried away on a stretcher. His condition was unclear although he appeared alert.

Strong winds caused the fire to spread from the vacant house at 90 Chestnut St. to the two adjacent triple-decker homes, one at 84-86 Chestnut St. and the other around the corner at 19-21 Willow St.

Neighbors said construction workers could be seen in recent weeks fixing up the vacant building, which had boarded-up windows.

Narrow alleyways separate the three homes.

Andre Cameron, of Boston, was inside the first-floor unit at 84-86 Chestnut St. with his children when he said he heard a noise that sounded like it was hailing.

"I was in the bedroom and I happened to lift the blinds and out the window I could see the house next to us, the whole side stairs were aflame," Cameron said.

When firefighters arrived, all three buildings were ablaze.

"The three buildings were pretty well engulfed on arrival," said McCabe.

He said it appears as though there may have been a delayed alarm.

Pitta praised the work of the firefighters who kept the blaze contained to the three buildings.

"They had quite a situation on their hands when they got there with all three buildings going," said Pitta. "The guys did a fantastic job making sure the fire didn't extend to any other buildings."

Manpower and water supply were challenges in battling the fire, McCabe said.

He said battling the fire was a "tough go" for the first hour or so.

"It took awhile to get the manpower and supply established," he said.

Fire hoses stretched all the way down Chestnut Street to a hydrant located in front of the Lowell Housing Authority unit at 117 High St.

Mutual aid responded to the fire from as far away as Lawrence, Methuen, Nashua and Pelham, N.H., Wilmington, Burlington and Haverhill.

Fire crews also responded from Tyngsboro, Chelmsford, Tewksbury, Billerica, Dracut and Westford.

Thick smoke engulfed the entire block between Chestnut Street and East Merrimack Street. White smoke could be seen blowing down as far as Bridge Street.

With Saints Medical Center located nearby, McCabe said he had not heard that the smoke had impacted the hospital.

Jorge Santos, who lives on the third floor of 84-86 Chestnut St., had been getting groceries when he arrived home to find firefighters battling the blaze.

He said he told firefighters his two Chihuahua dogs were inside his apartment.

"They're going to check, hopefully they're there," said Santos.

Santos lived in the apartment with his wife and three children, ages 10 to 8 months.

"Everything that we own is in there, I don't think nothing's good," he said.

The Salvation Army served dinner last night to those displaced by the fire in a church hall near the scene of the fire, Powers said.

The Lowell Transit Authority brought residents from the church to the emergency shelter opened by the Red Cross at the Lowell Senior Center on Broadway Street.

The Red Cross is working to ensure the displaced residents have the clothes and medications they need, Powers said. The city is putting together blankets and cots.