Firefighters arrived around 3:30 p.m. to a house filled with smoke and two people trapped inside, WGN reported. The 69-year-old man removed a window and dropped his grandson into the arms of officers waiting on the ground, WGN reported.
The man then collapsed. He was removed from the house by firefighters and taken to a hospital, where he is in critical condition, WGN reported.
The boy was taken to a hospital and is in stable condition.
A firefighter was treated for exhaustion and is expected to recover.
Investigators are still working to determine the cause of the fire.