Todd spoke of the legalities surrounding this event, which I agree with 100%, but beyond that I know that I would have warned any and all folks camped in the immediate vicinity that a bear was acting up and to beware.
Whether or not there were any legal obligations is not even an issue in my mind. To expect all campers to be knowledgeable about the wild is ridiculous.
To me it is akin to warning, or stopping, a blind man who is about to step into an open manhole. He treks along, tapping each side of his path with his cane, but missing the middle. He has no reason to expect danger.
I wouldn't want to live with the responsibility of having done nothing.