Report 4649: Women hear late night vocalizations at Sand Bar Flat Campground

We were staying at Sand Bar Flat campground, when my mother and I heard a scream that lasted for two hours, not far from our tent.  It started at about 2:00 a.m. and ended around 4:00 a.m.  There were probably two individuals, as we heard return calls down the river from where we were. I am familar with mountains lions, bears, and other animals, and this was not one of them.