Footsteps in Coos County, Oregon

I wasn't going to report this incident, but I believe it is of major importance to the Bigfoot research community. I will try to keep it simple. I had recently purchased a used vehicle and we decided to take it for a test drive to Laverne Park, which is just a short drive into the mountains from where we live. I was with my girlfriend, her 14 year old daughter, and my dog. After passing the park, we drove on further to see the country. We found a right turn and followed the rural road up into the forest. I later found out that we were traveling up Moon Creek. Not long after heading up the road, my car started overheating. I didn't have water on me so I decided to stop at the first water source, which was a bridge of the creek. I pulled over and we got out. While stepping out of the truck by girlfriend said, " hey, there is something walking on the hill above us". We stopped and listened for a moment but it was quiet. I then looked for a place to collect some water from the creek but it turned out that the edge of the water was too steep to step down and get water from. So, I had come up with a quick plan to connect some string to a cup and "fish" the water from the bridge. While we were trying to get the cup to fill, a small stone was thrown at us and bounced on the concrete of the bridge we were on. I looked up and noticed a steep hillside above us wondering what the hell could throw a rock at us. I noticed my dog was sitting in my truck, which she never does while I'm out of it in the wilderness. I was getting a little spooked so I tried to speed up the process of getting the water in the cup. Then, another stone bounced on the bridge next to us. I literally watched it skip along the cement. I mentioned that we better hurry, and then, from somewhere up the hill, came a very large rock, about the size of a softball of larger. It smashed against a huge rock in the creek and busted into pieces. I stood up on the bridge, looked at my girlfriends daughter and said, "let's go now!" My girlfriend and dog were already in the truck when I slammed the hood down and dove inside. We drove down the mountain and pulled over. I had left so fast that I didn't put the radiator cap back on. I considered returning after getting water to try to get pictures, but my girlfriend wouldn't let us go back. Now, either somebody was on that steep hill in the middle of the forest screwing with us and throwing rocks, or something else was. If it was a person, they are mighty brave in a forest full of hunters and guns. I don't know, seems awful strange.