Speaking as a 27-year-old guy who likes Quake, thanks. :p The gaming thing annoys me -- okay, on that logic, let Homeland Intelligence lock up ANYBODY with a copy of Risk! ;-)
As for who it is, the truly scary thing is: We don't know. There just isn't enough information yet for anybody here to definitively be able to say much of ANYTHING...we know some limited, non-useful information, like it COULD be a paramiliatary type, but an amature who has spent some time at a gun range COULD PULL THIS OFF WITH A SCOPE. Easy. There haven't been any headshots, and there are some people who've survived -- I'd say paramilitary would have left a bit more gore. But that's just my opinion -- I don't know a darned thing. I WILL, however, argue vehemently against anyone who wishes to advance the "videogames and tv led to this" idea. ;-) Things like that can be triggers, but you have to be already dangerously psychotic to no longer be able to draw the distinction between a game and life. Again, a trigger if you're ALREADY a dangerous sociopath. It doesn't MAKE people dangerous sociopaths. No more than collecting guns makes that person a "whacko gun nut" who's on a mission to form his own militia. :p
--KL
I'm sure we all agree on that, but it's worth repeating...