I found myself thinking that attempted murder maybe wouldn't be the right charge because you have to prove intent, but then I thought what would happen if it wasn't a cop doing the shooting? Odds are decent attempted murder would be the charge. And if it was someone who shot at an off-duty cop (without knowing their identity)? Guaranteed attempted murder charge.
Face it private citizens: Cops are just above the law.
Historically, in the vast majority of civilizations, when the government becomes out of line, a revolution happens. This is more difficult in modern times because of crazy advancements in technology, however, it *will* still happen.
It is only a matter of when.