The exact reason you should be armed at all times. What do you do when the police are not there to save you or your children, or when they are too cowardice to do their fucking jobs. I am armed, and if my child was in that school, I would have added another 19 bodies to the death toll. You would have had to kill me to prevent me from saving my child.
The parents might have risked a charge of false accusation to suggest to those "Police" that there was a drug lab in that classroom.
Strike that, the "Police" know where all their drug labs are located.