When firefighters arrived Thursday, the second floor of the house was engulfed in flames. One woman was able to escape.
She and neighbors reportedly tried to get inside to find the child. Firefighters searched through heavy smoke, but the victim had already been killed.
East Joliet Deputy Fire Chief Kirk Kelly said the blaze was reported at 1:15 p.m. at 1354 Sterling Ave. in unincorporated Joliet Township, the Joliet Herald-News is reporting.
"The bedroom door had burned halfway through as we got there and went all the way through the door as we were there," Lockport Township Fire Capt. Joe Casagrande said.
The fire took about an hour to extinguish.
Two women watching from a nearby corner collapsed in sobs before one was taken to the hospital for emotional distress.
Elwood, Frankfort, Homer Township, Manhattan, New Lenox and Rockdale firefighters assisted.
The Sun-Times Media Wire contributed to this report.