I like to think that no sane adults are in favor of children taking guns to school. But what do I know? People basically don't have guns where I live.
In Japan rifles and shotguns are legal, but the licensing procedure is lengthy and difficult, and those weapons are only allowed for hunting and for skeet and trap shooting. No one without a licence is allowed to hold a gun. The police have pistols, but only the holsters are actually visible.
It's not for me to say any other country should do the same, but it's probably the biggest reason some Americans choose to live here or in other countries with strict gun control despite certain inconveniences.
And, of course, some monster who wanted to go to a school and kill a bunch of toddlers could use a bomb if obtaining firearms were too difficult.