Multiple Victim Public Shootings, Bombings, and Right-to-Carry Concealed Handgun Laws: Contrasting Private and Public Law Enforcement.

Originally written in 1999, this analysis by John Lott Jr and William Landes, makes an interesting read in the context of recent events, Virginia's concealed carry law, and Virginia Tech's insistence that it not participate.

VIII. Conclusion
The results of this paper support the hypothesis that concealed handgun or shall issue laws reduce the number of multiple victim public shootings. Attackers are deterred and the number of people injured or killed per attack is also reduced, thus for the first time providing evidence that the harm from crimes that still occur can be mitigated. The results are robust with respect to different specifications of the dependent variable, different specifications of the handgun law variable, and the inclusion of additional law variables (e.g., mandatory waiting periods and enhanced penalties for using a gun in the commission of a crime). Not only does the passage of a shall issue law have a significant impact on multiple shootings but it is the only law related variable that appears to have a significant impact. Other law enforcement efforts from the arrest rate for murder to the death penalty to waiting periods and
background checks are not systematically related to multiple shootings. We also find that shall issue laws deter both the number of multiple shootings and the amount of harm per shooting. Finally, because the presence of citizens with concealed handguns may be able to stop attacks before the police are able to arrive, our data also allows us to provide the first evidence on the reduction in severity of those crimes that still take place.