Assuming you know all the facts, what room were they in?
How many kids were in the room? How many rooms in the school could the murderer have been hiding in?
Did all the shootings occur in one classroom or were there multiple classrooms the shooter entered?
Did the classroom doors have locks? Did the shooter enter multiple rooms to kill kids or did he enter one room and shoot all the kids in that room?
Did the LEOs know exactly what room the shooter was in or did they have to do a search on all the potential rooms the shooter may have been hiding in until they found him?
Was the room where he was finally located locked or barricaded or what?
Since I admit that I have no answers to those questions it's reasonable to assume you don't either.
And since you don't, you have no right to question the actions of the LEO's who responded until the final report comes out......
Arm chair Rambo's are annoying........
Even I have enough common sense to know if you may have children hiding from an active shooter you don’t ask them to call out.