Nobody wanted them to "just go in shooting." I expect police to be good enough shots not to kill kids in the crossfire, particularly when the kids were on the other side of the room from the shooter. Most of the police were wearing vests and a few had shields. They shouldn't need 77 minutes to form a tactical approach.
If they're just going to stand around saying, "Ooo it looks dangerous in there, I'm not going in," then they should find another job and quit collecting regular pay as police who tell us they aim to serve and protect citizens.
We know how many kids died when the police weren't there. In one classroom 100% of the children were shot to death, none of them had a tactical plan, a bullet proof vest, a shield or a gun.
I doubt that.