[ThermoNuclearWarrior]

Someone having a gun isn't going to guarantee a better ending to something like this, but it does significantly improve the chances of it. You don't hear about these types of shooters having shootouts very often because they commit suicide or surrender as soon as they are met with force, or usually before they are met with force, but know it's close. I think this guys mind would have turned towards retreating and surrender as soon as someone shot at him. There are several other cases where evidence shows the shooters in those cases would have likely committed suicide as soon as confronted by an armed civilian the same as they did when confronted by law enforcement.

[dfwgator]

The point is, if somebody is contemplating committing a crime, he isn’t going to very likely pick a target that he knows a certain number of people in the building are likely to be armed.

If a thief has a choice of two houses to rob, and he knows one house has armed inhabitants, he isn’t very likely to pick the armed house.