Neighbors said the boy was unable to hear or speak.
Fire officials say there were no working smoke detectors in the home when flames ignited at approximately 10:30 p.m. Sunday night.
The medical examiner has identified the victim as Sergio Pedroza, 11. His body was found inside a bedroom on the first floor of the two-and-a-half-story red brick home.
Witnesses say his mother tried desperately to save him. Neighbor Rosie Cisneros happened to hear the heartbreaking screams from the mother calling out for her disabled son who was trapped inside a burning room.
"I do know he was handicapped. He couldn't hear. He was mute, but he was able to walk," Cisneros said.
Witnesses say the mother tried to get back into her first-floor apartment, but there was too much fire.
"The mom is screaming for help. Her son was inside. There [were] more people inside; they had just gone inside, but when she opened the door, the flames were too strong for her to go in to try and attempt it," said Cisneros.
Firefighters say they were able to keep the flames confined to the first floor after an aggressive attack.
"The heavy fire was on the first floor. Unfortunately, we have a child...from the room of the fire origin that did not make it," said Steve Chikerotis of the Chicago Fire Department.
"Knowing the way he was, he probably hid, if anything. But I do know the mom heard him screaming when she was trying to go inside. So, she heard a few screams and then she didn't hear anything at all," said Cisneros.
Four adults were rescued with no major injuries.
Firefighters broke out windows and used ladders to rescue two residents from the upper levels of the building and took them to safety on a ladder.
Moses Barco says he lives in the garden unit.
"By sheer luck -- what saved me, what got me out of there. I started smelling smoke, and you don't need a smoke detector for that. It's sheer common sense. So, [I] just got out and that was it," Barco said.
According to fire officials, the blaze was extinguished less than an hour after it started.
The cause of the fire was not known Monday.
Firefighters returned to the area Monday to stress the importance of smoke detectors and to pass them out to those who need them.
" If we can say something to the general public about smoke detectors, they do save lives, so that's the message for today," said Chicago Fire Department Chief Mark Nielsen.