1) You cannot completely protect anybody from the actions of others. If you keep weapons out of the hands of the insane, the criminal, and the violent, you will have to limit everyone’s access to weapons. Potential weapons include practically everything: firearms, cars, trucks, planes, boats, sharp objects, insecticides, prescription drugs, and on and on.
2) The most recent deranged killer was a Neo-Nazi. Nazi are not extreme right, as noted by the press. They are extreme LEFT. Why, in Heaven's name, doesn't anybody stand up and say that THE NAZI PARTY IS A SOCIALIST ORGANIZATION!
This little secret is why the left wing teachers union doesn't teach history in the classroom anymore (unless they think a historical figure was a homosexual).
Today, they teach Social (Socialism) Studies instead.
Whenever I hear a young skull full of mush supporting the democrats agenda, I mention this. At first they don't believe me, but my confidence gets them thinking, especially when I laugh and tell them to check it out for themselves.