POTEET, TEXAS -- Atascosa County sheriff's deputies are investigating the death of a 6-year-old boy who was shot and killed by his 15-year-old cousin.

Deputies said the 15-year-old boy and 6-year-old Kenneth McKenzie Buscher were alone inside the teen's home in the 300 block of Post Oak Drive at 4 p.m. Sunday when a 12-gauge shotgun the teen was holding accidentally went off, killing the younger boy.

Chief Deputy David Soward said the 15-year-old, who has experience handling weapons, had removed a round from the chamber and thought the gun was empty.

"This boy, he'd been hunting for several years and knew how to handle firearms and practiced firearm safety, according to his father," Soward said. "But we still have an accident because they're kids."

The teen's mother had been watching the two kids but had stepped outside the home with a friend to smoke a cigarette when they heard the shot coming from a bedroom.

"In this area, everybody has weapons, and that's fine, but if you have weapons in the house, the guns need to be kept in an area where they're not accessible to children," Soward said.

Having a loaded firearm accessible to a child under the age of 17 is a Class A misdemeanor, Soward said.

No charges have been filed, although the investigation is ongoing.