If you'll excuse my generalised social mathematics:

Bullying + Unstable Personality + Teenage Hormones = Suicide

Bullying + Unstable Personality + Teenage Hormones + Guns = Suicide or School Shootings

You're fifteen. The bullying has reached the point where you feel you just can't go on. Perhaps in later life, this would seem minor in perspective, but when you're fifteen, it's the worst thing you've ever felt. Is this adult life? If so, why on earth should you want to live it?

You decide you want to end it all. You can:
a) easily aquire a gun, kill bullies, kill yourself; avenge your own death.

b) Kill yourself quietly; make it quite clear that they've won.
I'm not condoning bullying; I was bullied a lot at school, although not to the point of considering suicide (which happens very rarely in the UK, but occasionally). But take away the guns, and at worst you have one death. One which, to divorce myself from emotion, may actually make the bullies consider what they've done, rather than just say "He was crazy!" and move through life with a clear conscience.

Yes, the bullying is the root of the problem. Yes, the media frenzy is giving the idea of shootings to kids who'd otherwise not have thought of it. But yes, taking the guns away would at least be an excercise in damage limitation.

Seeing as fondue's contribution has again slipped into the void, I'll add some of the points he made. Here in the UK, we have never had a student-perpetrated school shooting. This is not because we say prayers every morning, care for our children more, or restrict violent video games; we don't. It's not because we drink tea. It's because guns are illegal, very hard to obtain illegally, and utterly unavaliable to angst-ridden teenage students.