My wife and I were off the trail to take some photos since she works as a model and I wanted to get some pictures of her by the creek. There was one small Volvo or Audi parked at the trail head when we went into the trail and signed the Login Registration at the Trail Head. We had been at the location for 30 mintues, when we heard a very deep sound almost roaring sound from a very large mammel. I am an expericenced pack packer and had years of experience in boyscouts and have had many encounters with Bears, and on occasion, have had to take food bags away from a very large bear that stole a hikers food near avalance pass in the High peaks. I have heard Bobcats and Coy-dogs and this was no animal that I had ever heard, including a possible bigfoot sighting I had nearly 10 years ago. The sound was so distict , so low, almost a cross between a scream and a growling sound. I had never heard anything like this in all my life. It made the hair stand up on the back of my neck. I have never been as frightened in all my life. I tried to keep my cool with my wife who frightens easily. The sound came closer and closer and was coming from the other side of the creek from the trail. It make this blood curdeling scream/yell at least 7 times as it approached us and at one point it was about 25 feet away. As it came through the woods, we could hear large branches breaking and could tell it was starting to circle us. The sounds stopped, but we could just feel it looking at us. We were in total fear and we quickly gathered our things and ran down the trail, the whole time we could hear this very large animal tracking us to our right side along the creek.