You should read the book Columbine by Dave Cullen. He was a journalist on the scene that day, and he spent ten years doing the proper research to make his book as factual as possible. It's an amazing read, and it has a lot of insight into the lives of the kids that did it. There were warning signs. I think that everyone should read that book and see what they were doing before they did what they did. Maybe then people would pay more attention and notice who needs their help.
Interviewer: "If you were to talk directly to the kids at Columbine or the people in that community, what would you say to them if they were here right now?" Marilyn Manson: "I wouldn't say a single word to them. I would listen to what they have to say, and that's what no one did."