The boys and their mother were visiting a 78-year-old neighbor in their apartment complex when the shooting occurred. The two boys found a semi-automatic pistol "somewhere in the living area," according to the AP, and then took the firearm into a bedroom. The gun went off and the younger boy was shot in the head. Payson Police Chief Don Engler told the AP that the boys' mother was just walking into the bedroom when the shooting occurred.
Engler said his department is investigating, and will send the results of its investigation to the Gila County Attorney's Office.
"What we're taking a look at is the circumstances regarding the securing of the weapon" Engler told the AP. "We are continuing our investigation, and we haven't ruled out criminal charges at this point."
The names of the two boys, the mother, and the neighbor were not released.