MERCER, Pa. A man's handgun went off while he was holding it as he got into his truck in the parking lot of a gun store Saturday and the shot killed his 7-year-old son, authorities said.

Joseph Loughrey, 44, was getting into the truck when the 9 mm handgun discharged, wounding Craig Allen Loughrey in the chest, according to State Police. The boy died outside the Twigs Reloading Den in East Lackawannock Township, 60 miles north of Pittsburgh. Store owner Leonard Mohney said he didn't see what happened in the parking lot.

Investigators said Loughrey told them he didn't realize there was a bullet in the chamber. "This happens all too often where people think the gun was empty," Lt. Eric Hermick told The Pittsburgh Tribune-Review.

State Police said the shooting was being investigated as an accident.