The Department of Buildings say the owner of a Bed-Stuy brownstone has been issued a violation for illegal construction after a fire displaced three families and injured a firefighter on Monday.

Citizen app video shows flames spreading through a brownstone building on Monroe Street near the corner of Marcy Avenue at around 7:40 p.m.

More crews had to be called shortly after the initial crews arrived to get the fire under control at around 10 p.m.

Residents in neighboring buildings had to evacuate when the fire that started at 283 Monroe St. spread quickly.

"It happened so fast," says Brian Jackson. "I didn't really have time to think, just grabbed my kids and go."

The FDNY says after an initial collapse, everyone was pulled from the building and they continued to fight the fire from the outside.

Video also shows pieces of the roof falling down after the first collapse.

The Department of Buildings tells News 12 that there were interior gut renovations going on without permits.

They say the owner of the building has been issued a violation for illegal construction.

The fire chief tells News 12 that a firefighter suffered minor injuries after a floor collapsed below him. The fire chief says the firefighter was able to walk out of the building on his own.

Officials say no one else was hurt.

Assistant Fire Chief Joseph Jardin says there were some serious concerns about the stability of the building, and there were several collapses both inside and outside.

"It seems to us the building was under renovation," Jardin says. "We had a firefighter initially on entry fall through the floor, that's how we discovered the building was compromised due to renovation. And as we were preparing and removing members, there was a significant collapse in the cornice."

Officials say the fire appears to have started on the second floor, but spread up to the third floor and to neighboring buildings through the windows and holes in the ceiling.

The Red Cross tells News 12 they are helping three families find a place to stay.