Where Were the Police?
My advice, if you are in an active-shooter situation, is the same no matter your age. Listen for the source of the shooting. Give yourself at most two seconds for this task. Those are not firecrackers. Then run as fast as you can in the other direction, and do not stop running until the only thing you hear is the sound of birds chirping, wind in the trees or grass, and the beating of your own heart.