When parent's drop their kid's off to school or when a child is in school they're not thinking someone will enter their school and hurt them. This should not be on anyone child's mind. No parent ever should have to worry that harm will come to their child/children when they are at school!!

A lot of change must be done. It should never be that easy to purchase a rifle. Background checks need to be put in place. 

As for the schools all schools should be be armed with cops not just security guards. No one should be able to enter the school unless they are buzzed in. It should not be easy to enter any school.