After Ross puts his hand on the rock, he kills his wife and attacks the group. It is shown that he has murdered a bunch of people as the camera pans to multiple dead bodies next to him. Basically when people touch the rock they become blood hungry demons-like creatures who are captivated by the grass. Their souls are trapped in the field forever and they trick other people in. They are then forced to relive the same tragic fate over and over again at the hands of Ross and the other grass-faced people.