Chicago Fire Department officials said the investigation was handed over to Chicago police detectives because of possible criminal activity.
A ball of fire raged atop a two flat apartment building on the 4700-block of West Ohio Street in West Garfield Park.
Hours later, all that remains is the building's shell, with everything inside, charred in the inferno.
"All of our stuff is ruined," a woman who lived in the apartment building said. "Like we have nowhere else to go. We don't know who else to contact or anything."
The woman said she wasn't home at the time of the fire. She said she spoke with her family about what happened.
"It sucks to have a house and then get burned down, like out of nowhere. Out of the blue," she said.
Chicago police said the fire broke out just after 11:30 p.m.
Fire officials said it began in the building's rear porch from open flame ignition with what they call "available combustibles."
Dozens of firefighters could be seen working to put the fire out smashing windows and using flashlights to search the building.
Displaced tenants wrapped themselves in Red Cross blankets to stay warm.
Police said a 33-year-old man was rushed to Loyola Medical Center with burns to his face and arms in critical condition.
The woman ABC7 spoke with anonymously says people used a ladder propped against the building...to pull that severely injured man from the building's second floor...which was engulfed in flames
"One of the people who got injured was screaming out for help - like it burns, it burns! Help me someone, help me!" she said.
Two other people, an 81-year-old man and 64-year-old woman were also taken to Mt. Sinai Hospital in serious condition to be treated for smoke inhalation.
Sadly, one family's dog, did not make it.
"Rest in peace Luna," she said. "She got burned with the fire, as well. We couldn't save her... "It was our home, and now it is gone."
Investigators are still working to determine what sparked the fire in the first place.