Call me crazy, but I will always give a twelve year old child the benefit of the doubt before I shoot to kill. The best move would have been to keep their distance and simply talk to the child. Why they felt the need to roll up on on the park grass that fast I will never understand. How about simply asking the child in a nice adult tone "hey their buddy, what have you got there? Can you put it down so I can look at it for a second?".