I'm surprise no one brought this up. Ever wonder why mass shootings usually happens at a gun free zone? Anti gun group such as Every-town or MDA wants more gun free zone. However, when a mass shooting happens, in one of those gun free zone, they ask "Where is the good guy with a gun?" trying to prove that conceal or open carry doesn't help.
Most law abiding citizen respect those gun free zone, and when a mass shooting happens, they wonder why there's no "Good guy with a gun"
A shot doesn't have to be fired, for a conceal carry hold to stop a bad guy. I'll bet most of you don't know about this regarding the oregon mall shooting. Take a look for yourself.
https://www.youtube.com/watch?v=6dsV6TCwd0o