Eugene Volokh asks this question in an article at the Washington Post and gives some examples of civilians that have stopped a mass shooter or shortened the time a mass shooter has to kill:
Backers of laws that let pretty much all law-abiding people carry concealed guns in public places often argue that these laws will sometimes enable people to stop mass shootings. Opponents occasionally ask: If that’s so, what examples can one give of civilians armed with guns stopping such shootings? Sometimes, I hear people asking if even one such example can be found, or saying that they haven’t heard of even one such example….
6. In Colorado Springs, Colo., in 2007, Matthew Murray killed four people at a church. He was then shot several times by Jeanne Assam, a church member, volunteer security guard and former police officer (she had been dismissed by a police department 10 years before, and to my knowledge hadn’t worked as a police officer since). Murray, knocked down and badly wounded, killed himself; it is again not clear whether he would have killed more people had he not been wounded, but my guess is that he would have.
7. In Edinboro, Pa., in 1998, 14-year-old Andrew Wurst shot and killed a teacher at a school dance, and shot and injured several other students. He had just left the dance hall, carrying his gun — possibly to attack more people, though the stories that I’ve seen are unclear — when he was confronted by the dance hall owner James Strand, who lived next door and kept a shotgun at home. It’s not clear whether Wurst was planning to kill others, would have gotten into a gun battle with the police, or would have otherwise killed more people had Strand not stopped him.
8. In Pearl, Miss., in 1997, 16-year-old Luke Woodham stabbed and bludgeoned to death his mother at home, then killed two students and injured seven at his high school. As he was leaving the school, he was stopped by Assistant Principal Joel Myrick, who had gone out to get a handgun from his car. I have seen sources that state that Woodham was on the way to Pearl Junior High School to continue shooting, though I couldn’t find any contemporaneous news articles that so state.
Eugene notes that many people have never heard of examples of civilians stopping mass shootings. I think some people are just playing dumb because they don’t like the idea of people fighting back and it fits their narrative to think nothing can be done in these cases.
However, there is also the fact that the media rarely reports on people fighting back or using a weapon to stop any crime, much less a mass shooting which is rare. I have often noticed that if someone stops a crime with a weapon, it is mentioned briefly in the back of the paper or article or not mentioned at all.
It is no wonder people think it rarely happens. Maybe if people read the Armed Citizen in the NRA magazine, they would have a different idea about one’s ability to stop crime with a gun. Of course, nothing is perfect and weapons are only a tool, but they are often the only means of defending the defenseless.
More from Dr. Helen: