The earliest known United States shooting to happen on school property was the Pontiac's Rebellion School Massacre on July 26, 1764. That day four Lenape American Indians entered the schoolhouse near present-day Greencastle, Pennsylvania. They shot and killed schoolmaster Enoch Brown, as well as killing nine or ten children (reports vary). Only three children survived.
One of the worst massacres happened in 1927 in Bath Michigan. 45 were killed at the school including 38 elementary children using bombs not guns. The man was a school board member and blew the school up with dynamite and pyrotol. He then drove his car up to the school, called over the superintendent, confessed he was responsible and then detonated his car as a car bomb filled with dynamite and shrapnel killing and injuring several more people along with himself. The event killed 38 elementary school children, two teachers, and four other adults; at least 58 other people were injured. Their deaths constitute the deadliest mass murder in a school in United States history. The event is the third largest non military massacre ever in US History behind only 9/11 and the Oklahoma City bombing.
I posted this for perspective to the people trying to blame liberals or conservatives, or guns, or knives, or baseball bats, or whatever. People are responsible for this....evil people throughout history who are mentally unstable. There's no law you can pass to prevent the nature of demented individuals in doing something like this. I’m sure this will offend some, but feelings are a poor substitute for reason when laying the foundation for laws that only the lawful will follow.
The man in Michigan in 1927 (a school board member!) wanted to harm and kill those innocent people and used the means at his disposal. In the Oklahoma City bombing the guy used a rental truck and explosives constructed out of common farming chemicals/fertilizers. In the case of 9/11 they flew planes as ballistic projectiles into the innocent.
There is no total defense against those who make the choice to do these things. However, we can often be ready and vigilant. It isn't the weapon...as all of these incidents show. It's the guy choosing to use whatever means are available to attack the innocent.
It may at times be demonic in origin.... it may be organic brain damage....it may be chemical imbalance causing brain synapsis to fail....it may be mental/psychological breakdown....or even a personality breaking....but there are normally signs. The METHOD is not the issue....it is the person... and we need to be able to better identify them before they strike.
These individuals have been in all history....this is not a new issue.
link for more information on the Bath, Michigan tragedy
http://en.wikipedia.org/wiki/Bath_School_disaster