By disarming the citizens in these areas, you are just turning them into potential kill zones.  Most of the places that have had mass killings in the last few years, have had several things in common.  First they are areas where a lot of people are, such a government buildings, and second they have been gun free zones.  Facts are that if a person is planning on break a major law like killing people, a regulation that states they do not bring a gun into the building is not going to stop them.  The only thing that will stop them is another armed good citizen with a gun.