Look, I don't want to start an argument about gun control, because its a really tight subject to argue, but I will say this: Yes its true that guns CAN save lives, however on the flip side of that there wouldn't have been a need for the victims to own a gun in the first place if the attacker never had a gun either.
I know that is essentially a cop-out, so I'll add another comment, again not trying to start a giant argument: Another thing to keep in mind is that none of these people are trained to use a gun. I don't have an issue with people owning guns, I don't think thats the issue with gun control. The issue that I see is that people abuse what should be a privilege. It doesn't take much for someone to grab a gun and look intimidating with it to try and rob someone, but it is NOT the same for the cashier who has a gun in self-defense. The cashier is panicking, his nerves are racking, and on top of that he has a gun to his attacker. He's not thinking clearly, and can do something very dangerous to anyone accidentally. THAT is the issue in my eyes to gun control. If people want guns to defend themselves, then there should be training and knowledge that needs to be implemented before people can buy a gun. That way the lower-level criminals who simply pick up a gun and start waving it around are at a disadvantage when they come up against someone who knows how to handle a stressful situation with a dangerous weapon.