Good grief! Where's the childrens parents? Also, why don't the police shoot out the tires of cars to stop them or to slow them down?
Because you have to be at a certain angle to have a chance of hitting the tires; the target is very difficult to hit; meaning that bullets will go flying around in a varying background (which may include people); if you do hit the tires and they are certain types of steel radials, they may simply bounce; and if you do manage to overcome all of that and puncture the tire, it may not stop the car.
Shooting at tires is really bad judgment.