It would appear from this story that this gun somehow accidentally fired itself. No one seems to know where it came from; it seems to have been on a lone rampage (much more at the link).
An Arkansas man assumed the boy wrapped in a blanket on his futon was his sleeping cousin. But hours later he realized it was a 14-year-old boy he didn’t know who, police determined Thursday, had been shot while playing with a gun with a friend.
Little Rock police said the boy, TyJuan Woodard, died after he and a 13-year-old friend were playing with a gun that accidentally fired and shot him in the chest Wednesday.