The injured are being treated at Loyola University Medical Center's burn unit. They are expected to survive.
On Friday, investigators were back at the home looking for clues to what started the fire.
"The area of origin was in the basement and it traveled up in the walls, which makes it dangerous for us because there was a lot of hidden fire in there," said Commissioner Robert Hoff, Chicago Fire Department..
The fire was so hidden that Sharhonda Lathan had no idea a fire had broken out. Lathan, her 10-month-old son Casimir and three other relatives were eating dinner when a neighbor, who saw fire on the top floor, ran in to warn them.
"I'm like this playing with my son, and she was like, 'the house is on fire.' We thought she was joking until we seen the tears in her eyes," said Lathan. "Once we made it out, it just started rolling. Everything was rolling, and you just seen flames, flames, flames, flames."
A total of four firefighters were hurt. Most seriously injured were 31-year-old Gerald Carter and his captain, 52-year-old Tom Ruane. Both are from Engine Company 54.
"Captain Ruane, he's a very great man. He knows his job. He knows what to do, and he's always looking out for people," said Antonio Artis Jr., Chicago firefighter.
"Gerald came here two and a half years ago out of the fire academy. A very conscientious young man and very aggressive, and he was learning the job," said Lt. John Leonard Chicago Fire Department.
Officials say both men were overcome by flames on the second floor. When Firefighter Carter stopped moving, an alarm signaled for help. A five-person rapid intervention team, whose sole job is to rescue firefighters, sprung into action.
"Stretchers, ladders, extrication tools. You name it, they have it," said Tom Ryan, president, Chicago Firefighters Union Local 2.
Within minutes, the men were out of the burning home.
"That's what this rapid intervention team program is for. It's for us. And it saved one of our own," said Battalion Chief Sean Burke, Chicago Fire Department.
Lathan and her relatives say they lost everything in their home. Right now they are staying with a neighbor. She is grateful to the injured firefighters.
"Thank you. And I'm so sorry for the ones who got injured, but thank you so much," she said.
Officials say they don't know what started the fire or what caused that flare up on the second floor which injured the firefighters.