It could be done. A timer to detonate the car or truck bomb (even a cell phone!), a run to the camp with enough ammunition for a small war, an "assault weapon" that will fire both full- and semi- automatic (and plenty of practice with it), and a lunatic desire would be all that was needed. The killer would be familiar with the local police set-up as well, and would rightly expect that the bomb would be occupying the police while he did the rest of his filthy work. The fact that a helicopter wasn't readily available is not surprising; our local police would have a hard time rounding one up in a hurry. Because this is a public forum and I don't want to give people more ideas than they already have I won't discuss what I see as the criminal's failures.