It sounds cold of me to say so so soon, but that is the direction this has to be pushed.
America has tried the disarmed people zone thing at schools, theaters, malls, and the result invariably has been a target rich environment with little or no opposition for any demented malicious person who pops up.
We know no law can eliminate the guns in the hands of the determined. It has not worked anywhere it has been tried, even to the point of outright bans. Only letting people have a fighting chance to defend themselves and the innocents around them will mitigate the effects of the diabolical, not surrender.
It must be made unthinkable that anyone would even attempt (crazy or not) to harm such as those children--a swift and sure death would be assured.
“Abstinence doesn’t work.”