I read the report on the Virginia Tech massacre. Everyone should read it. The kid (shooter) didnt talk to anyone except his sister for approx 20 years. This self imposed silence followed open heart surgery when he was 2 years old. (The report should be still available on the Virginia Tech website). You can see how little effort it took to render the University Police totally ineffective. (The shooter did not have a scanner).
In general, Campus Police can do very little to prevent mayhem. I wont go into any details here.
Boston PD and Boston Transit PD recently decided not to issue more assault rifles to police officers. because it is seen as leading to an escalation of violence. And I see encryption as leading to an escalation of violence. Check out "death squads" at Wikipedia. Police are mentioned several times. Clearly, not all police are bad. But just a couple of bad police with encrypted radios and assault rifles would be a disaster.
Peter Sz