Said her son: "I was scared."
I still am. Prayers for this child and the family.
They seem to have settled on the .223 as the round of choice. Not hard to see why, as hateful as its effects have been on the victims. Do any of these come with collapsible stocks that would make them easier to conceal or stash for someone else to pick up? There used to be an AR-7 .22 survival rifle (not the same thing, to be sure) which could be broken down into a small package. The single-shot tactic could lend itself to this; a single-shot .223 could be easier to break down and conceal, or even disguise as a non-weapon. Something to consider until disproved.
Also, watch home-schooling become more popular. Not that there weren't reasons before.