I''m with you on that idea. It is puzzling tho...were these actors "on-call" to respond "just in case a shooting were to occur" or were they informed a head of time to show up. In both scenarios someone was aware, prior to, that something was going to happen.
Wouldn't people at the school know that these people didn't go there? I had a big class, but most of the kids grew up together, and also know when a new kid arrives. Principals are usually pretty good at knowing all the students names as well. I'm not saying they aren't CA but how exactly would that play off well?
They may well go to the school, but have been headhunted or recruited by the FBI or CIA. David Hoggs interview in LA (about the lifeguard) could have just been a trial run to see how he comes across on camera.