Easy availability of arms and ammunation is the basic reason.
Tolerance level of the young has dwindled.
Bring power and God back to the schools and school systems. School property belongs to the school. Behavior, if bad, can be punished. It is a learning institution where teachers and staff deserve and demand respect at all times. Back to the “board of education”, suspension, repeating a failed grade. No one was murdered by monsters, not a loving kind man but monsters during those days.
I believe everyone going into school should have to go through metal detectors just like going into a courthouse. After school has begun they also need to put the school on lockdown, so no one can enter. Maybe they need to give everyone that needs to be in that school a pass and put some kind of entry system in. All others would be forced to use an intercom system and then be searched before entering the school.
Only the State should have the so-called monopoly of violence. Abolish the right to bear arms if you don“t need them (for instance, if you want to become a hunter and need a license). In a civilized society you should be able to rely on police protection and not just on the right of self defense.
Read the Bill Dedman on MSNBC today. Very educational treatment of a very heartbreaking subject.