Glenn Reynolds links to the story on the "security guard" who stopped the shooter at the Colorado church--it was actually a parishioner who had her own gun handy along with a concealed carry permit, not a security guard as noted by the media.
As Glenn Reynolds noted earlier this year, people don't stop killers, people with guns stop killers.
I find it funny when talking with my friends from overseas. Many of them assume everyone in America has a gun and will shoot you dead in the street if you look at them wrong. Of course, most law abiding people in America don't have guns-but just about every criminal does. I don't have a weapon, in large part as deference to my wife who can't abide them. However, as more of these incidents like Colorado happen, where the involvement of a properly permitted, law abiding, Second Amendment loving Americans with a gun no doubt saves lives, I begin to wonder if getting a permit and a weapon is not such a bad thing. The Navy taught me how to shoot and I have a talent for it, but I also have the common sense and training to use my skills properly.