Chances are you can't. Unless they are all knocked out sleeping and you bash them one at a time, really quietly.
I think a better example of something that can kill massive amounts of people at once would be automobiles, and planes. We don't ban those. Anyone who wants to ban guns totally is misguided and is for punishing people for crimes of others, myself as a marijuana enthusiast would be very hypocritical if I stood by the banning of anything.
Saw a dem on tv today trying to compare home gun owners to that of sex offenders. The discussion was based on gun owners info being published. Sad thing is this guy has absolutely no gun knowledge to make any claims period.