It's pretty scary stuff.  The guy obviously had some sort of grudge - if Dimebag was a drunken arse, then it's likely that he ticked off a fair few people - but why he would then turn on the crowd is incomprehensible.  They were just there to listen to the music.

It's a shame that the guy was shot dead by the police - although he deserved everything he got, we'll probably never know what his motivation was and will never stand trial - sounds like an easy way out.

Reminds me that Stead and I were talking about the Hungerford massacre the other day.  There's just no way to prepare against something like that.