Virginia Tech: Is it our fault an individual would commit such a crime?

I know that in the past, students have gone on shooting rampages because they had been bullied or didn't fit in. It sounds like this time, it was over a fight or breakup with his girlfriend. He just lost it and went over the edge. I don't think it is anybody's fault that he chose to do this. He had 2 hours between the first 2 he killed and then the 31 others. He had time to rethink what was going on and he chose to continue his killing spree. There is no telling what is going on in a person's mind like that.