You are completely over-reacting to point of absurdity. As I've said, I'd keep my child home tomorrow and see how she felt and what security steps were being taken for the following days.....and where she'd be with that emotionally. If I believed that she'd be safe and she wasn't emotionally upset, then off she'd go. But I would want to know steps were taken in the area for hers and the other children's safety. The sniper might still be in the area, ready to go to a school in this neighborhood....
I would take security steps taken by the schools with a grain of salt. They have all sorts of security measures here, to protect the children from the gangs and "bad guys", and I can see ways to circumvent most of them. Besides, the sniper can always shoot through a window.