They weren't the shooter, just the Sargent giving the statement.
I'm gonna side with the cop on this one, the kid could have atleast said something about getting their phone. If I were a cop and saw the person I was arresting/talking to start reaching for something in their pocket without saying anything at all I'd shoot too. As for the kids age, kids are getting worse each year, I know 14 year olds who shoot up so I wouldn't be too shocked if some young kid was packing a gun.