Even had he known it was a 12-year-old, he would have been fully justified in shooting her to protect his life and the lives of other bystanders.
That's how it is when you play in the big leauges.
So if we lose the brakes in a vehicle and an officer is nearby, we may be killed. Nice.
Of course, if he shoots the engine or better yet, the tires, he might stop the car.