Report 1617: Three hikers see something cross their path

I left an open can of jack mackerel 20 yards up from our campsite. A couple hours after we went to sleep something wandered into our camp, omitting quiet high pitched noises. Then the can of fish came rolling down the hill past my tent. Thinking it was a bear I loaded my .22 rifle and shot up to scare it off. Then this huge creature ran off through the swamp. From the noise it was making one can assume it was big, whatever it was. So we got out of our tents, built a fire, disposed of the fish and talked about it for 20 min. or so. Shortly after we went back into our tents loud screams came from the other side of the lake. I've a good amount of time in the woods and I have never heard anything even close to what I heard that night. The screams went on for 30 minutes. We were shooting our rifles, yelling, banging pots, and this creature just kept on making these horrible screams, similar to the screams I have since heard of Bigfoot on recordings. One can dismiss the idea of a human playing a joke. What human in their right mind would continue to make these noises after we started shooting? From what I have gathered on the subject of Bigfoot my experience was a little uncommon.