Recent school shootings and violence in schools

I've heard some of the people in my classes talking about recent shootings and school, and while I think I have commented on this topic before, I felt like doing it again. I was browsing google and came across this listing that reported some shootings worldwide, though I'm sure it's not extensive in the least because I don't even believe I saw the Columbine shooting. Why years after years are shootings and violence still occurring in schools? Are teachers seen as the ones responsible for some of this violence by not preventing it? Is it further adding on to the bad rep teachers receive?
In the past week, I believe there has been 3 or 4 US school shootings! What is going on? At this rate, schools won't have to worry the risk of Bush's "No Child Left Behind" act to close them down, but they'd close from lack of students or too much fear in families and them not allowing their children to go to school. The latest school shooting I had read about was one at an Amish school. People presume that city schools and schools in minority neighborhoods are probably most prone to violence, but an Amish school and several of the others don't fit that assumption; thus, this isn't just an urban problem but a world, practically American problem. It's like death, no one is immune to it. I'd been telling my mom ever since I entered the education school how I was dieing to be a teacher, but I don't want to die while teaching. How can such an inspiring profession have such dark and dangerous shadows.
If anybody has any opinions on these recent shootings or on any sort of violence in school, such as how do you go about breaking up fights, or anything, I'd be interested to know what you think. I'm really looking forward to teaching, but I don't want to have to fear for my life at the same time.