Most classrooms have windows in their doors don’t they?
You’re right... It sounds like the police are making excuses.
According to the article at the thread below, police stood in the hallway, assumed everyone in the classroom was dead, and figured they had the killer contained to one room.
https://freerepublic.com/focus/f-news/4066768/posts
Officials admitted on Friday that nearly 20 officers stood in a hallway outside of the classrooms during the attack, believing any potential victims inside were already dead.
'Of course it was not the right decision. It was the wrong decision,' Texas Department of Public Safety Director Steven McCraw said at a news conference.
The on-site commander 'was convinced at the time that there was no more threat to the children and that the subject was barricaded and that they had time to organize' to get into the classroom
Just... speechless.