Screaming or howling in Snohomish County, Washington

About 12:30 PM that afternoon (October 13) one witness who had just arrived mentioned when I arrived about 15 minutes after him that he heard a lot of commotion out by the Sauk River that sounded like someone was out hunting with hounds and they were baying like crazy, possibly having something tree'd. This is not uncommon in this area as some locals do hunt cougar and bear with hounds here. Although it is illegal to kill cougars they do "tree" them for sport. Later that evening around 5:00PM the same witness had gone down the bank by Bachman Creek to relieve himself and when he came back commented that something seemed a little strange and there was a different odor in the air down by the creek and felt a little "creeped out" by it. We started a campfire at about 7:30 PM. The campfire is located about 20 feet from the edge of a creek running through a sapling filled older riverbed. At 8:20 PM, as we sat around the fire conversing, a distinct, loud, and very close vocalization occurred that literally stunned us all into silence. There were two distinct parts to the sound and overall lasted only 15-20 seconds. The first part lasted about 12-15 seconds and consisted of a whooing/moaning that was very distinct and close, right at the far edge of the creek I would guess. Followed by a 2-5 second pause and then a booming, paralyzing scream that lasted about 5 seconds. The reactions within the group varied with two of us quickly putting the fire between us and whatever was making this sound, the others just sitting in silence. We immediately heard movement in the dark…not loud but obviously something moving from left to right on the far side of the creek (maybe 30 feet away). Then nothing. One of the witnesses who has lived, fished and hunted in this area for over 40 years swears he has never heard anything even close to this vocalization…and really does not want to again. The next day we found no obvious sign in the creek immediately out from the campfire. Leaves had started covering the ground so it would have been difficult to find any sign. The next day a friend and I hiked up the creek and river approximately ¼-1/2 mile and found a fresh sapling broken/twisted off at about 10 ft. and the top section thrown out onto the rocks at the river edge about 15 ft away. At the river edge, in a sandy area we found barefoot prints…small, maybe 9” but with strange toes. Not human? Who runs around on a river barefooted in October with temps in the near freezing? After doing a closer survey of the area we found several different sets of tracks in what looked to be 3 or 4 different sizes with the largest being about 17”. We went back the next day and cast several of these tracks.