Flames ignited at a two and one-half-story brick apartment building in the 1400-block of South 50th Court.
Eyewitness News was told everyone was evacuated from the building.
Neighbors rushed outside to see what happened.
"It's terrible. I just pray and hope everybody got out safely," one unidentified woman told Eyewitness News.
No one was injured. Warming buses were at the scene to keep the apartment fire victims warm.
Meanwhile, hot spots rekindled Wednesday morning at the three-story warehouse in the 1800-block of 54th Avenue, just blocks away from the apartment fire. That warehouse was engulfed in flames in Tuesday night.
The fire started around 6 p.m. and spread from the abandoned warehouse to a nearby building. The fire was fueled by cardboard contained in that neighboring building, which houses a business called Central Steel Fabricators. Firefighters were trying to protect a third nearby building from the fire because it contains flammable chemicals, including paint thinner.
This fire was so big that a 3,000-foot line was used to bring water in from Chicago. Firefighters were rotated every 15 minutes due to the cold weather, and for that reason, reinforcements were called in from fire departments in Oak Park, Berwyn and Hinsdale.
Complicating matters were the frigid temperatures that froze waterlines.
"With the ice conditions, right when you open up a hose line, the streets were a sheet of glass. We're falling, everybody's trying the best they can. We have salt trucks out from the town. It's hindering us very much," said Chief Ron Opalecky, Cicero Fire Department.
Cicero's fire chief said that he expects to be fighting the fire all night, and that hot spots will be likely over the next two days.
So far, no injuries have been reported.