The boys' father, Michael Santiago, was charged with felony child endangerment and is being held on $75,000 bail, according to the AP. He told police that he used to be a gang member and kept the gun for protection, Assistant State Attorney Joseph DiBella said. 

"About a week prior to the shooting, he showed his older son where he kept the gun" wrapped in pajama pants, DiBella told the Tribune.

"(Santiago) took the gun from on top of the refrigerator, unwrapped the pajama pants and explained to the 6-year-old that the gun was only to be used by adults."

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