Listed here are heresay reports; they lack any proper evidence (photographs, video, audio, etc.) but are still important to note, due to the sheer amount of them and the credibility of some reporters.
"It begins in 1924, when a group of miners were working in the Mount St Helens range in Washington State, seventy-five miles north of Portland, Oregon. One day they saw a big ape-like creature peering out from behind a tree. One of the miners fired at it, and thought the bullet hit its head. The creature ran off into the forest. Then another miner, Fred Beck - who was to tell the story thirty-four years later - met another of the "apes" at the canyon tim, and shot it in the back three times. It toppled over into the canyon; but when the miners went to look there was no body. That night the miners found themselves under siege. From dusk until dawn the next day the creatures pounded on the doors, walls and the roof, and rocks were hurled. The miners braced the heavy door from inside, and fired shots through the walls and roof. But the creatures were obviously angry and determined, and the assault ceased only at sunrise. That day the miners decided to abandon the site."1
For more information: Ape Canyon Incident of 1924
1The Mammoth Encyclopedia of the Unsolved by Colin Wilson and Damon Wilson (2000).