IIRC, there were a number of programs put into effect in the wake of Aurora and Sandy Hook. They came down to two philosophies

First:
1) Run
2) If not possible, then Hide
3) If discovered, then fight. I recall airline passengers, in the wake of 9/11, being instructed to throw luggage at any high jackers.

Second: ALICE, intended for schools and compartmented buildings like office buildings.
Alert
Lockdown - IIRC, this is where Sandy Hook went very wrong. The substitute teacher did not have the classroom key to lock the door.
Inform (realtime information on shooters location)
Counter - Fight. Ever get beaned with a flying laptop?
Evacuate - self explanatory

For reference and giggles
http://www.wrbl.com/story/27832442/valle...school-shooters