Once again Jim says it very well. The bottom line is this, criminals carry firearms where it is illegal to do so all of the time, by definition they have no respect for the law. Rest stops in SC were initially illegal places to carry a concealed weapon with a permit when the SC carry law was passed. They have since modified the law because they found that they had made a safe haven for the criminals, while insuring that the law abiding would be unarmed victims.
Take a moment to think about why some of the most horrific crimes have been comitted in schools. Do you think that the schools were targeted for no reason? The schools were targeted because these individuals knew that nobody would be able to stop them from doing what they wanted. Would you put a big sign on your home that says "GUN FREE ZONE", I know I wouldn't and I cannot fathom why we would put our children at risk by doing this. Again the bottom line is that a bank robber is not going to stop robbing banks because it is illegal for him to carry a gun in one!
Violent crime has gone down in every state that has a right-to-carry law, while violent crime continues to climb in areas with the strictest gun control (i.e. DC and Chicago). Even criminals are not complete idots. In Florida when they first passed their carry law, gangs and criminals started targeting tourist at rest stops (i.e. people with out of state plates) because they knew that they would be unable to defend themselves. Florida determined this by interviewing the perpetrators. They then modified thier carry laws so that they now issue permits to non-residents, and this drastically reduced this problem.
Criminals will, by nature and definition, always target the weak and defenseless. This is part of the reason our founding fathers gave us the constitutional right to keep and bear arms (on top of the consumate check and balance on government).
If you look throughout history, the most horrific genocides comitted, were comitted on people that did not have the means or right to defend themselves.
Hitler first required the Jews to register thier firearms, then he required them to store their weapons in the local armories and shooting clubs, then he confiscated them and continued to exterminate them.