WTF - Another Columbine

I can't begin to grasp what must go through a person's mind when they commit an act like this. By now, I'm sure you've read about it, the boy in Minnesota who killed his grandparents and then went to school and started shooting up the place before turning the gun on himself. WTF? This has truly got to be one of the all time biggest WTFs because it just makes absolutely no sense. He wasn't stark raving mad, depressed, obsessed with Satan or any of those things according to the people who knew him. He was just a teenager. What's the driving force behind an act as senseless and horrible as this? As much as I'd like 2 know, I know that even if it could be defined it would still make no sense and I'd still be saying ...

What the f*ck???