Screaming or howling in Pierce County, Washington

Well, my dad had taken me, my sisters, brother, and step mother out for a day of 'rock hunting' so that he could find the rare and odd rocks that he loves to go and find in the mountain areas. Me and my younger sister were walking along a trail that my step mother and youngest sister had just come from, they had said it was a nice trail and that we should check it out. So we did. About...a fourth of a mile towards a half of a mile down the trail me and my sister stop at this little creek, we stay there for a while playing in the water, I wanted to continue down the trail, but my sister freaked out on me, telling me that she had a very bad feeling and wanted to go back to where my dad and the others were. I told her it was ok and eventually convinced her to head down the trail a bit more, however once we started off again something charged at us from a wooded hill that was right next to me. We heard this horrible terrifying howl/growl coming towards us as the trees and bushes moved around as if a truck was coming through them. All i saw was a black figure and I started running, I yelled to my sister to get the hell out of there, me and her both cursing and running as fast as we could over the trail, now that I recall the trail was a dirt bike trail, i still don't know the exact location, it was a while ago. Anyways as we ran back I fell and hit my ribs, i couldn't run any longer and looked back to make sure whatever the hell it was, wasn't chasing us, and nothing was there, my sister wouldn't stop so i had to keep going, even though I was so out of breath I couldn't run anymore. She wouldn't stop. When we got back we were both crying and so scared that we left right away with everyone because we couldn't stay there any longer. We were to scared. I thought at the time it was a bear, or a cougar, then on the way home i realized those don't sound like that, i know what those sound like, and whatever was chasing us did not sound like a bear or cougar. After hearing some prerecorded, suposed, whoops and howling from bigfoot in my area, it got me scared becuase they sounded so similar to what me and my sister heard