First there is something we all must realize. Even though we feel we live in a safe, secure, and peaceful society, the reality is that this is a facade. Fortunately (or unfortunately) the facade generally stands - bad things don't often happen to nice people. Every once in a while however, violence slips out through the cracks under pressure much like a hernia. When this happens, it's usually innocent people caught in the crossfire - and generally caught unaware.
Most (if not all) schools (and employers, and government buildings, etc) explicitly do not allow weapons on their premises. This makes for a unique situation where anyone with a weapon in these locations become the most powerful person there. Essentially, any armed crazy, evil, malicious, or scared person is a wolf in the chicken coop. So, anytime we have a campus shooting, it almost always ends up a massacre. There is literally no one (save the few police officers in a nearby area), that can balance the power of the one armed, bad-guy.
It is a terrible tragedy when innocent people die through violence. When it happens in America it is all the more poignant however, as we believe we are safe from such barbarism (it actually happens all too often in many other parts of the world I'm afraid). While we certainly get angry at the evil-doer, we never seem to look at what we (every one of us individuals - not mommy and daddy government) could be doing differently.
In the backlash of situations like Virginia Tech and Columbine, the first thing we generally hear is: "we need stricter gun control!" Unfortunately, this is not something that will prevent (or defuse) such atrocities! Gun control laws do not affect criminals with malicious intent. Period. What they do do is render law abiding people defenseless against violence as heinous as a campus shooting.
Because of our our misguided attempts to prevent violence, we have created myriad defenseless victim zones all around our nation. Had any one of the students involved in the Virginia Tech shootings had a firearm themselves, chances are very likely that the death toll would not have reached 32. The plain and simple fact is that power must always be balanced.
When very bad things like Virginia Tech happen, the first thing we must all ask is: "Why didn't anyone else have a weapon to stop this guy?" When we don't have to ask this question, our peaceful facade will be reinforced and the great many innocent Americans can go on feeling safe and secure because the people who know better are around to protect them.