What stands out the most to me is that no one thought there’d be kids inside until they think to check a classroom almost half an hour into the standoff. It’s the middle of a school day, there are school district police on site. This is awful.
Yes, it’s absurd! They knew where the guy was, as far as those kids knew the officers finally opening the classroom doors could have been the gunman. A teacher was standing right next to that first door when it opened, I can’t even imagine how terrifying that would have been.
And they still took forever to evacuate! If you’re going to clear the area before going in you’d better do it instead of waiting around for someone to give orders.