ABC7 captured video as firefighters worked the scene in the 2000-block of North Lorel Avenue on the city's Northwest Side.
Officials said the fire had been struck by 5 a.m.
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At least two people, a woman and a child, were taken to Stroger hospital in serious condition, the CFD chief told ABC7.
Both were taken out of the house by CFD's ladder, the chief said.
They're expected to recover.
No other injuries were immediately reported.