People have been killing each other since the beginning of time. Remember Cain and Abel? Before the gun was invented, people used fists, rocks, spears, arrows, swords, knifes, fire, water, trees, rope, reptiles, animals, insects, poison, etc., to killed each other. The Romans even made entertainment out of killing people. There is no reason to think if guns disappeared from the face of the Earth, the killing would somehow miraculously stop. Guns don't kill people, people kill people and unfortunately humans have excelled at the skill of killing.