Yeah, such a quandary. Simply mind boggling. Only one way into a school that is comprised of several single story buildings with windows, doors and a/c vents but somehow the only point of entry to save 600 kids is that one door. And not one sharp shooter in the bunch to end it while he’s focused on that one door.
No, the cops isolated him in that room so he would not have access to the rest of the school. That is the way I understand it anyway.