Taking off impossibly fast in Snohomish County, Washington

Saturday May 9th my girlfriend I and were returning from an overnight camp off the Mountain Loop Highway. I wanted to find a place to shoot that was off the road and away from any trails, the river, or possible campers. Found a spot that didn’t have a car for more than a mile each way. Pulled over and loaded up about 10 magazines. Spent about 15 minutes getting everything ready on the tailgate of my truck. Heard absolutely nothing but birds chirping. I hiked down a ravine to the left of the road about 150 yards and shot off some rounds for about 15 minutes. Finished up and walked back up to the car where my girlfriend had been waiting. As soon as I came out of the ravine and onto the road we both heard a LOUD cracking / snap noise from the top of the wooded hill that was to the right of the road, the opposite side of where I had been shooting. We both looked at each other wondering what it was, our jaws dropped. It wasn’t a tree breaking because we didn’t hear anything hit the ground. There was also no wind less a sporadic slight breeze. We heard the noise approximately 6-7 times and there was about 30 seconds between each one. It was very loud and very, very close. The time between each one was also very consistent. My girlfriend and I both said that we could hear it coming form the top of the hill maybe 100 yards from the truck. We could also hear something moving around. Not twigs and branches snapping but it sounded like bark rounds being stepped on and ripping. A strange noise, it actually sounded like something ripping bark from a tree too. I grabbed my cell phone and walked up the hill to where the sound was coming from. Filmed about ten minutes. I was filming up and to the right of the hill for a good 6 minutes. As soon as I walked a little closer to the top of the hill and started filming to my left another cracking sound rings out, startled the hell out of me because it was so close. The camera actually shakes when the noise starts from me reacting. This was just about seven minutes into filming. I heard the sound of bark or something again, like it was peeling off a tree. I couldn’t help but think that the sound was coming from up in a tree. I got it on my phone and you can hear how loud it was, and how close. I would guess whatever was making the noise was about 50 yards away. Returned to the car and left. I thought it was very strange that this noise didn’t start until after I made all the noise shooting. When I made it to the area where the noise originated I could see my truck. It’s like whatever made the noise waited until it saw me get back on the road. The noise it made was so loud I am perplexed as to what it was. It sounded like a large branch being hit on a tree and snapping. I can’t think of any animal that makes any noise that loud. I’ve spent countless hours in the backcountry and camping and have never heard anything like it. As much as I wanted to climb the next 50 yards to the very top of the hill I couldn’t bring myself to do it. I had the feeling that whatever the hell was making that noise was protesting my being there. I still had my pistol on me but it was loud enough that I decided to head back to the car.