While I haven’t been employed in a capacity that would likely put me in a position to be one of the first LEOs on the scene for quite a while, I have tried to keep somewhat abreast of general changes in response tactics. The biggest was several years ago after a tragedy was that the first on the scene try to form up a team with what they had and enter. That was in response to policies requiring SWAT to handle entries. I don’t know what was really going on down in Uvalde, or what the policies were, but it sounds like a team was formed with who was available on the scene at the time. Also, if the gun fire is suddenly silent, no one inside to call out the killer’s location, and the building square footage is large, the team may have to search. And of course there’s no cookie cutter active killer template, these situations, while having some commonality, are also evolving. Individual skills, primarily being able to communicate, move tactically as an individual responder or as a team, and being able to consistently shoot accurately are still highly critical - probably the three most important beyond the individual commitment to enter in the first place with just what you’ve got.