I don’t know if the classroom in question had an external wall, but with 20-20 hindsight, even a “dynamic breach” of the door and even an exterior or adjoining wall might have had a better outcome.
That is, blow the door and blow in a wall at the same moment. There are water-damped demo charges that will just create an instant entry through cinderblock and other materials. Of course, the risk is some kids might be hurt/killed during the dynamic breach, but the good side is that even the shooter is going to be stunned senseless while SWAT pours in.
Of course, any harm to kids/teachers will result in lawsuits etc, hence the “caution” and 21 dead.
> water-damped demo charges that will just create
> an instant entry
It looks like a tiny town; Texas is big and it seems to have taken SWAT time to travel there. Not every police department has explosives training - and you probably know better than I do that it’s not simple to place charges without potentially killing or injuring the tiny folks inside.