This is from a report entitled, "When Seconds Count: Stopping Active Killers":
The other statistic that emerged from a study of active killers is that they almost exclusively seek out "gun free" zones for their attacks.
In most states, concealed handguns are prohibited at schools and on college campuses even for those with permits. Many malls and workplaces also place signs at their entrances prohibiting firearms on the premises. Now tacticians believe the signs themselves may be an invitation to the active killers.
The psychological profile of a mass murderer indicates he is looking to inflict the most casualties as quickly as possible. (emphasis added)
"...I advise the gun. While this gives a moderate exercise to the body, it gives boldness, enterprize, and independance to the mind... Let your gun therefore be the constant companion of your walks," Thomas Jefferson