Firefighters this morning were still putting out rekindled hot spots after an extra-alarm fire gutted a strip mall in the North Side's Peterson Park neighborhood Friday afternoon, according to fire officials.

Parts of the building rekindled several times overnight, which is a common occurrence after large fires, CFD spokesman Larry Langford said. Firefighters went "back and forth" between the building and their firehouses and have managed to contain the new hotspots, he said.

No injuries have been reported from the fire, which may have been sparked when roofers used torches on the building's roof, fire officials said.

By a little after 6 p.m., the fire was considered under control, but some of the more than 200 firefighters who responded to the blaze continued to pour water onto the strip mall from several ladder trucks. Cars parked on North Albany Avenue stood up to their bumpers in a lake of water next to the building. The fire caused power to be cut off to hundreds of homes in the area.

The fire started just before 4 p.m. in the 3100 block of West Peterson Avenue, according to the Chicago Fire Department. After determining that the blaze was too strong to fight from the inside—and that the building was of a type of construction prone to collapse during fires--firefighters set up a defensive perimeter and a collapse zone. At one point, what were likely propane tanks on the roof caused a series of explosions.

"We believe those were propane tanks left on the building by the workers (on the roof)," said deputy fire commissioner Michael Callahan. "One of them may have been, and I haven't confirmed this, a transformer in the alley."

The roofs of at least two buildings collapsed, Callahan said, but nobody was hurt.

Most gutted was the Mid-America Furniture store at the strip mall while an American Mattress store and a For Eyes optical shop were also "destroyed," according to the department's news office.

Callahan said 207 firefighters helped control the blaze.

"It's under control," he said around 6:30 p.m. "It's not going to be out for a while."

During the fire, black smoke enveloped the whole neighborhood, blocking the view of the moon from north of the fire, with streets closed off for blocks around by police. Smoke could be seen as far east as Broadway in Rogers Park, several miles away.

Water filled surrounding streets as the choking smoke invaded neighborhood homes.

The fire was raised to a 3-11 alarm about 4:39 p.m., and a 4-11 a little after 5 p.m. with heavy fire reported throughout the structure, according to the Chicago Fire Department's news office. The building's roof had collapsed by a little after 5 p.m. It was declared under control just before 6 p.m.

The fire was raised to a 4-11 alarm so there would be enough equipment on-scene to manage the massive amounts of water needed to suppress the fire. A firewall in the building that cuts off the north section of the building from other parts of the building was holding, according to the Fire Department.

CTA buses were rerouted in the area.

Ruth Guillermo lives near the intersection of Hood and Whipple, a few blocks from the fire.

Around 6 p.m., thick smoke still filled her block.

"You can smell the smoke inside the house," said Guillermo, who watched the fire rage from her second story window.

Guillermo said her hairdresser and a liquor shop both had businesses in the strip mall.

"I've been praying it would not get into the liquor store," because of the danger of explosions, she said.

Tribune reporter Adam Sege contributed.

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