[url=http://www.vcstar.com/rescue/]read the accompanying story here.
According to that article, once the rescuers made initial contact, the rescuers yelled and the hikers yelled back. Apparently, the distance was so far that they were basically just communicating noise (and flashlight beams).
There were no whistles? OK, I know it's easy to armchair quarterback, but this seems like the textbook moment to be using a whistle and S.O.S. (by flashlight beam and/or whistle). It seems like the hikers were otherwise prepared. I'm confused.