Rumors were some kids knew the day before that something was going to happen and stayed home on the day of the shooting.
If so, all of this was out in the community ahead of time and almost certainly some parents would have called friends who were teachers or staff to find out WTF was going on in order to make a decision whether their kid should stay home or not.
Staff, then, was most likely told to shut up and carry on. One teacher sends the kid to the office for gun drawing, I think. Was the shooter that obvious, or was the teacher hyper tuned in to whatever the fuck the kid was doing at any given moment? Smart teacher. if the latter.
School has a psychologist and SRO, according to their website, and they should have been in the meeting when this particular kid, basically with a prior gun issue from the day before, got sent to the office.
Story was, kid was told to get counseling, and was suspended but the parents didn't accept the suspension, so the kid goes back to class.
Psychologist would have made the counseling call, can't see the principal doing that on their own, and if the kid was suspended, but refused to leave, then the SRO collars him and calls the local LE to arrest him for trespassing.
I've been in this situation, but without a shooting. Gun threats,. Kid was coo coo. Kid out of school and for the next week or so the school was swarming with Staties with rifles. Sniper tactics engaged, too. In every nook and cranny.
The Sheriff in Oxford already hung these fuckers, too. If they destroyed evidence, as is being reported they need to be arrested and the State dept. of Ed. and LE needs to take over the school.