There's no simple way to really do it but if you take away all the guns the folks who are doing shootings will consider other means of taking life. Probably more extreme rather than less. It's not a gun issue. It's a responsibility and mental health issue. It takes a village to raise proper healthy minded individuals and there's science to prove it.
Children who are not brought up favorable conditions tend to have issues. And no that doesn't just mean poor financially. Rich kids have it too.
@MrGoat I agree in mental health. Not sure I agree about more extreme methods of murder. Even with YouTube it takes know how to build a proper bomb for major effect without blowing yourself up. Cars, yes you can drive down a sidewalk or promenade, etc. But for how long? What other methods can do as much damage as guns, especially in closed spaces?
@MrGoat again, most *effective* methods (as effective as an AR with high capacity magazine) take more training and experience than what is readily available now. It doesn't mean people won't find a way but it will take them a lot longer.