Emergency crews responded to the scene at a two-flat in the 800-block of Winchester Avenue around 8 p.m.
A neighbor who lives across the street told ABC7 Eyewitness News he saw the sparks and smoke as it ignited.
The Chicago Fire Department was able to put the fire out by 8:35 p.m.
It was not immediately clear which unit the fire started in, how extensive the damage was and whether any people or families have been displaced.
Chicago fire officials said no one was injured. The cause of the fire is under investigation.