From the original article: (which identified the girl as 5-years old)
A 5-year-old girl was injured early Saturday morning when a gun hidden between mattresses in a Marquette Park neighborhood home discharged as she was jumping on the bed, police said.
The girl was in good condition after being taken to Comer Children’s Hospital for treatment of an ankle injury, said Chicago Police News Affairs Officer Darryl Baety.
UPDATE (3/26/12): The girl is identified as 4-years old, and was injured in the ankle. The father is an ex-felon in possession of a stolen gun. From the article:
Jarquise Upton, 21, of the 6400 block of South Artesian Avenue, was charged Sunday with one count of felony unlawful use of a weapon by a felon, misdemeanor possession of ammunition and theft of lost or mislaid property, police said.
.Upton is accused of storing between two mattresses a gun that went off about 12:20 p.m. Sunday as a 4-year-old girl was jumping on a bed at his home, police News Affairs Officer Hector Alfaro said. The girl was shot in the ankle and treated at University of Chicago Comer’s Children’s Hospital.