Firefighters shattered windows and soaked all four stories of what had been a flaming four flat apartment building in the 1900 block of West School Street in Roscoe Village.
Large flames could be seen coming out of the building, which has multiple apartment units, witnesses told ABC7.
"I looked outside and it was just completely up in flames," said Rachel Klousnitzer, who lives nearby.
Klousnitzer rushed outside, cell phone camera recording, just before 6 p.m. to see fire raging through the brick building, shooting well into the air.
"It was terrifying," Klousnitzer said. "There was smoke all the way down the block. Couldn't really see or breathe. I would say the flames were at least 20 feet above the roof. It was terrifying... We were just so worried about all the other houses and potentially the people and pets that were home."
People were home in both buildings and scrambled to get out as wind swept flames from one building to another.
"We had fire on all four floors, so unfortunately those residents will not be able to go back to their home," Chicago Fire Department District Chief Shun T. Haynes said.
A few of the residents were left shivering, wrapped in blankets on the street in the snow, watching firefighters try to salvage their homes.
As crews tore through the brick building, knocking down walls and hot spots, one firefighter appeared to briefly faint, seemingly overcome with smoke, and was led away on a stretcher.
No injuries from residents were reported, CFD said.