This seems to be an excellent argument that everyone have a concealed carry permit (and a reasonably large caliber weapon at all times). Since "shall issue" was enacted; carry permits have, very substantially, statistically reduced crime in my community. Citizens who do carry stop crimes here all the time, it's in the news almost daily. Car-jacking used to be extremely popular here. Now it is drastically reduced (almost unheard of). It's a sad thing to realize that police virtually always arrive after the crime is committed; or less often, still in progress. The targeted victims, hopefully armed, are always there when it starts. Armed citizens stop far more crime than they commit.
e.g.
Not too long ago a knife wielding nut-case was shot dead in a fast food restaurant by one such citizen. Only the armed robber was injured. No innocents were harmed.