hammAR wrote:"...You can plan to deal with the security officer. You can't plan against random yahoos running around with guns..."
That is pretty much what Dr John Lott's research has determined as to how the perpetrators of mass shootings pick their targets.
The uniformed security officer is a known threat/ target.
an unknown number of armed staff is a deterrent.
The Santa Fe school had two armed police officers and had trained extensively in active shooter protocols, so it wasn't a situation where "good guys with guns" can solve the problem.
LINK
Sometimes you need more good guys with guns