Nope……..you just stop making those public spaces gun free zones…..let normal people carry their own guns……that will keep killers from attacking those places……the Colorado theater shooter picked the one theater in the area that was a gun free zone…other theaters closer to him alllowed concealed carry…

Other Countries Had Mass Shootings. Then They Changed Their Gun Laws. (Published 2022)
Britain, Australia, Canada, New Zealand, Norway: All had a culture of gun ownership, and all tightened restrictions anyway. Their violence statistics now diverge sharply from those of the U.S.