One of the first thing dictators do when they take command is remove the publics ability to defend itself.
These school massacres occur because the government has violated the Second Amendment of the United States Constitution by declaring "gun free zones."
These "gun free zones" violate the second amendment just as "free speech zones" violate the first amendment. When you remove a persons ability to defend themselves you essentially sentence then to death at the hands of these killers. If only one person was armed and ready to shoot that killer, we could have avoided this whole tragedy.
One such example was the Appalachian School of Law shooting where students who were armed and had concealed carry permits were able to subdue a shooter.
It is clear that the second amendment must be defended, for the public safety.