Police are trying to determine if the fire was deliberately set, a spokeswoman, Monique Bond, said. A series of smaller fires broke out overnight in the area immediately around the apartment building, The Chicago Tribune reported.
The fire was reported at around 7 a.m. Firefighters arrived within two minutes and found one man on the ground in front of the building, apparently after jumping to escape the blaze.
Larry Langford, a fire department spokesman, said the blaze apparently began in a second-floor stairwell in the three-story building. He said investigators had found no obvious signs that the fire was deliberately set.