My overseas cousin, PCX, emailed me about the Arizona murders. He wondered "If more people at the event were armed, the nut would not have been able to empty his Glock." PCX lives in Brazil, where personal possession of firearms is prohibited. The violent crime rate there is much higher than in the US.
Anyway, if another person at the event were armed, it would not have been politically correct. Guns are so icky-poo to to the left.
There are two reasons you might want to consider as to why this happening has so much play in the media.
First, it involves a "Democratic" Party gathering for its victims -- the obvious. But the push to blame the nut-bag's actions on the Republican/conservative movement has pretty much failed.
The other reason is if someone else were armed, it would have been resolved pretty quickly, as you suggest. The story would have been played out immediately. The Party controlled media would not be able to stand the idea that anyone should be capable of self-defense. The fact that it happens all the time pokes a hole in their whole people-must-be-controlled-by-government riff.
Still, one wonders....
I am glad Rep. Giffords is making a recovery. Since ObamaCare won't kick in for two more years, this horrible shooting shows what a fine medical establishment he and the "Democratic" Party have screwed with. Lets hope we can undo the damage.