I recall reading something on this form (Its source was Police One) about a hypethetical situation similar to this. It encouraged concealed carry by students (if they were in college) and the teachers to carry as well.
The problem is that 32 people died today, and many of those deaths could have been prevented by civilian CCW and proper police tactics. My prayers for all the families affected, the wounded, and the dead.
You're claiming that civilian CCW would have prevented this. That's almost certainly not true, at least in the first classroom. Weapons would have been in backpacks, not in easy reach, and the shooter would have the advantage of surprise as well.
CCW may have prevented him from moving on to a second room -- but that presumes that the armed students had some idea of how to respond. Otherwise -- if they're just barricaded and waiting -- the guy still has the advantage of surprise.
Not to mention the likelihood of "friendly fire" fatalities, caused by armed students firing over the heads of their classmates.
As for "proper police tactics," well .... how are the police supposed to respond to something like this, where the shootings would have taken much less time than required for the cops to arrive?