Camping at Yellowstone/Grand Tetons a few years ago. He set up our camper at an actual site and decided to do some two day long backpack trips in some of the longer trails. The second one we went to was Cascade Valley. Absolutely beautiful.
So get about 10 miles into the 22 mile loop and decide to set up our tent here since it was getting dark. We cook some food and chill for a bit before heading to bed. Around 2 am, we're all awakened by something just outside the tent. My mind immediately jumps to bears or wolves or something.
Then it starts talking. I will never forget it. "I think there's 3 or 4 in the tent. Let's just get out of here."
None of us could sleep the rest of the night. At the crack of dawn we high tail it out of there. Made excellent time. Hiked the 12 miles in about 3 hours and got to ranger station. Reported what happened, they said they had received a call similar to our story in the middle of the night. They sent rangers into the trail at dawn.
Never found out what was going down. Didn't hear of anyone getting hurt, but then again I didn't really look into it.