As a what-if exercise, I wanted to see what people's thoughts were about the report that someone (perhaps a student) had pulled the fire alarm to get people out of the building. Is that a good thing to do when some sort of mass attack is taking place?
The problem with that is, schools train to "lock down" during times of "active assailant" emergencies. They hunker down in their classrooms and barricade the doors. Pulling a fire alarm in that situation would cause mass confusion and scare the kids to death. The kids would be panicking, "Do I stay in my lockdown and burn up, or do I open the doors and make a run for the exits?"
I suppose the logic is that it gets people out and away from the danger.
Or away from their relatively safe lockdown, and INTO the danger. Made worse by their panic to "Get out of the fire, and not get shot/stabbed along the way."
If I were an insane student intent on killing/maiming my classmates, one of the first things I might do is pull the fire alarm. Multiple targets come pouring out of classrooms, and once they see their bloodied injured classmates they will panic and create all kinds of confusion. What better than a surging and confused crowd to hide myself in as I made my escape?
I think pulling a fire alarm, on purpose, as a way of "warning" people, would be a very very bad idea.