Police said the stabbing happened in the Gage Park neighborhood's 3000-block of West 59th Street around 7:20 a.m.
A suspect stabbed an infant girl inside a residence before jumping out of an upper-level window and suffering injuries, police said.
The victim was transported to Comer Children's Hospital, where she was pronounced dead. Her identity was not immediately released.
The suspect, whose age and gender were not immediately known, was transported to the University of Chicago Medical Center, where they were stabilized.
No other injuries were reported, and police recovered a knife from the scene.
The suspect is in custody, and charges are pending.
Police did not immediately provide further information about the stabbing.
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