The boy found the .45-caliber handgun in an upstairs dresser drawer and fired it through the floor, striking the man sitting at the kitchen table in the floor below, police said.
The 39-year-old gunshot victim suffered non-life threatening injuries following the incident, which was reported at 10:10 p.m. Saturday, Riverside County Sheriff's Sgt. Bill Davis said.
Carlos Santillan Serafico, 40, was charged with felony first-degree storage of a firearm, The (Riverside, Calif.) Press-Enterprise said Sunday.
Serafico was being held in lieu of $5,000 bail.