The intended meaning of my final paragraph was that if you find yourself drawing a gun on a disturbed 15 year old you're probably not much of a police officer. On the other hand, I don't know the details. Maybe by the time it had reached that point the kid was too far gone and they couldn't safely retreat. Of course, it should never have got that far.

Since a police officer isn't supposed to fire their gun unless it's the absolute last resort to stop someone killing someone else (or the officer) the shoot-to-kill policy makes perfect sense: guns don't hurt people, they kill  them dead. That's what they're for.