Ezra Stewart died at 6:25 p.m. Wednesday at Loyola University Medical Center in Maywood, the medical examiner's office said Thursday morning.
Chicago fire officials will pass out smoke alarms and fire prevention materials near where the fire occurred.
The home involved in fire did have detectors, CFD said.
The wife and three children of an on-duty Chicago firefighter were critically injured in a house fire Tuesday night on Chicago's Northwest Side.
The smoky fire broke out just after 9 p.m. in the 2500-block of North Rutherford Avenue, Chicago police said.
Firefighters rescued a woman, her two young daughters and son, who all suffered severe smoke inhalation.
The woman and two of the children were taken to Stroger Hospital. Another child was transported to Community First hospital, Chicago fire officials said at the time.
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CFD spokesman Larry Langford said the home where the fire occurred is that of an active Chicago firefighter, who was on-duty at the time of the blaze. He is a firefighter at Truck 55 in Edison Park.
Langford said the firefighter rushed to the scene after hearing his own address come over the scanner.
His fellow firefighters huddled around to show their support.
A neighbor said he heard a loud bang and looked out to see the home fully engulfed in flames. That's when he called for help.
"I was shocked. There was so many firefighters leaving, so many police. It's crazy. It hits so close to home, right across the street," neighbor Mildred Bran said.
Other neighbors rushed out when more and more emergency crews showed up.
"It was just smoke, really. The smoke that I saw visibly was smoke coming from the top of the home," said neighbor Joel Rivera.
Neighbors watched emotionally as paramedics rapidly performed CPR.
"I did see what appeared to be an adult being resuscitated," Rivera said. "It did not look like that person was in good condition."
Alderman Gilbert Villegas heard about the fire and planned to pass out smoke detectors in the neighborhood to remind residents to update their alarm batteries ahead of the time change weekend.
"We'll be doing a canvas today with my team and some 10-year smoke detectors that we'll be passing out," Villegas said.
The damage left on the home was visible early Wednesday morning.
Fire inspectors have moved in to determine a cause of the fire. Investigators wouldn't say whether or not the fire was intentional as the cause remains under investigation.
A deceased pet was seen being removed from the home Wednesday morning.
"They normally are outside. It's like three little kids. It's sad. Hopefully, everyone's okay," Bran said.
"I hope they're well, that they recover. I mean, we've just been praying for them," fellow neighbor Carlos Gomes added.