From the article:
The boy told police that at 9:15 a.m. when he went outside of his home in the 1600 block of W. 10th Place to bring his dog into the house he was carrying a semi-automatic weapon, said Cpl. Gabrielle King.
The youth saw three men in the alley nearby and confronted them. The teen told police he tried to hit one of the men with the gun and they started to struggle, causing the gun to go off and strike the teen in the right thigh.