I was not specifically considering classroom/ school shootings. Firearms, and missile weapons generally, decrease in usefulness as space becomes more confined. Such, at least, has been my experience.

The officers at Uvalde would have been better advised to rush the shooter with pepper sprays and batons (nightsticks?), than to hang around waiting for 'tactical' support. It's much harder to bring a long weapon such as a rifle to bear at close range and pistols are notoriously inaccurate at any range short of contact. In my younger days, in such a situation, I'd have gone in with my bayonet. Messy but effective. Nowadays I'd do as Boris Karloff did in Targets and use my walking cane!