Screaming or howling in Fentress County, Tennessee

myself along with my two best friends went down to see some family in tennessee during the summer for a few days. while down there we usually take some time to do some small game hunting. on our second to last day there we went back for about a mile or two to try and find the property line since the man who owned the land was in poor health and couldnt do it himself. he hadnt been able to go back that far since about 15 years do to his condition. we noticed the deeper we went into the woods we saw no animals and that was interesting to us. later that night we were at a small pond with a bonfire when one of my friends decided he needed to go back to the house. we had heard something pacing back and forth on a hill behind us, but we figured it was probably just a coyote or fox so we didnt pay it too much attention. he had a remington 870 shotgun with 6 shells of buck shot loaded anyways for the half mile walk back to the house by himself, on the front of which he had mounted a flashlight. about two minuites after he left we heard him fire all six shots in rapid succession. once we got to him he was scared stiff. all he could say was that something was staring down at him and show us how far apart its eyes were. we didnt stick around long thinking that he may have just injured a bear so we ran back to the house. once we got there he told us that he turned a corner to see the eyes staring down at him just off the path.. he yeld at the animal twice and it didnt move, so he shot. the animal was about 10 feet away and still managed to run off. well he went to sleep in the house and his brother and i went to go bed down outside in the barn loft. i had just laid down in my sleeping bag when i heard the most terrifying scream i have ever heard to this day. this animal screamed for a solid 20 to 30 seconds on one breath. i could tell that it was coming from the area we had just been however it was so loud even still i get chills thinking about it. it only let out one scream and then stopped. but as soon as it did, the entire forest fell silent. the only sound heard was the horse that had been spooked running around its stable. i didnt get much sleep that night. the next morning we had to leave so we didnt have much time to investigate the spot in the daylight. however we did confirm the spot where he saw the animal with a steep incline about 15 feet off the trail. i found no shot impacts from the shotgun even searching the ground leading us all to believe that the animal had been shot. since it had rained the night before the ground was still wet and i couldnt find but maybe one spot of blood. we tried to track it but we didnt have time and the woods were so thick that it was difficult to find any prints. there was only one deep indent which may have been a print but we couldnt tell. all i know is that the animal was big and still ran off after being hit 6 times with buckshot from 10 feet away and still had enough air in its lungs to scream as loud as it did for that long. i know a lot about animals and the only thing that i know of that could be that big would be a bear, but even a healthy uninjured bear doesnt make the sound this animal did. so i dont know what it was for sure but the only thing that makes since is bigfoot.