The smoke from the fire could be seen for miles as firefighters battled flames shortly after the blaze erupted at the abandoned building.
Firefighters arrived at the 5000-block of West Monroe Avenue to find smoke billowing from the burning building Tuesday morning.
Authorities said two people, a man and a woman who were inside the property at the time of the fire, managed to escape to the roof.
"I didn't think it was an abandoned building," neighbor Armetta Durr said. "At first they had all the windows in and then I saw a dog out there before, so I thought someone lived there."
CFD Battalion Chief Tom Fleischhacker said the people hurt in the fire seemed to be squatters.
"The whole basement and the first floor was all plywood and then people living up on the second floor," Fleischhacker said.
Officials said it appeared the fire started inside an enclosed area in the back of the building.
The landlord for an occupied building next door said this is not the first time there's been a fire at the building.
Alderman Jason Ervin, who represents the 28th Ward said the abandoned building has been a problem for a while because of squatters.
"One thing that I will talk about is the need for additional resources for individuals experiencing homelessness, because this is what happens when people just trying to stay warm we lose a building like this in our community," Ervin said.
The two people rescued from the burning building are expected to be okay, according to fire officials.
The city said it will secure the property.