You beat me to it...
I believe it was "myth #7" that talked about the fact that the police often (always?) arrive too late.
What people need to understand is that in a situation such as this, the police are irrelevant. I'm not saying anything negative about LEO's, I have the utmost respect for them. However, they are a reactive entity, they just can't respond quickly enough to do anything in most of these situations.
The Illinois shooting is just another example of a situation where, if people were not prohibited from exercising their Constitutional rights, the ending might have been much different. I guess the incident in Colorado Springs (CCW holder STOPS the bad guy before he achievs his goal) wasn't enough of an illustration for the boneheads in positions of authority.