Bad things happen in the world and I don't understand the mindset of people who wanna take away people's rights and abilities to defend themselves when such bad things do happen.
Yes their intentions are noble, but.. The predators will prey even more on their prey when their ability to defend themselves is less.
In my opinion the answer to such violence isn't trying to take weapons away, it's addressing the reason people pick up guns to terrorize or kill in the first place.
Crazy violent people will always find ways to mass murder, especially the more you take away the average persons ability to defend themselves.
The problems aren't weapons, the problems are why people use them unjustly. A knife or a gun can both unjustly kill or it can justly save a life, it's the user, not the tool.
Address the disease, not the symptoms if you really wanna try to heal it instead of putting a metaphorical bandaid over it that may make it even way worse.