Report 16350: Possible vocalizations heard from campground outside Okanogan

We arrived late around sunset to set up hunting camp and had finished setting the tent up and had started a fire.  No other campers were seen at this camp site, only we were there. the camp site was four-five miles in from hwy 20, with evergreen forest everywhere. sitting down at the fire, the scream commneced which sounded like a low tone scream which to me sounded like a fog horn going off with an abrubt stop after a few seconds. it sounded as if it could have been 1/2 - 1 mile away possibly from the top of the ridge. we were originally lost since this was our first visit and had driven the higer ridge just minutes earlier. if the scream was territorial it may have noticed my vehicle before maybe and screamed.