EDIT: I'm not advocating that carrying a knife is useless. A knife's day to day usefullness merits carrying one. I'm just arguing against the "unequipped victims" = likely target premise.
You can draw your own conclusions, but the vast majority of mass shootings in America's recent history (last 50 years) have been in "gun-free zones" or "weapon-free zones". The stats aren't even close to being the other way around.
I believe the empirical evidence is overwhelming that these cowards prefer to attack unarmed people where they gather; schools, churches, sporting events, restaurants, and shopping centers.
The presence of one or two trained concealed carry citizens would have reduced the carnage in most cases. This has been shown to be true many times with nothing but speculation to argue against it.
Removal of the 'guns banned here' signs probably would have totally prevented the incident in that specific venue.
I'm not a fan of the added sound or graphics on this video, but the content is good.
The suspects were both wounded and were arrested shortly after the incident.
http://www.youtube.com/watch?v=epZod2qyyN4