According to an article ran in the Fresno Bee in August of 1986, a five man construction crew was spooked by what they say was Bigfoot while working on a job.
The job entailed building a foot/horse bridge near the Pacific Crest Trail on the south fork of the Kern River in the Inyo National Forrest (roughly about 25 miles south of Mt. Whitney) and given the remote location the men were camping at the site where they worked. One day, as the sun was setting the five men heard a scream so loud and described the intensity of it as something that "sounded like a stadium loudspeaker. The scream came three more times, and one of the workers used a rifle to fire a warning shot in the air.
At that moment, four of the five men saw a humanoid figure several feet away from them. They weren't able to make out any details but say the figure was at least 8 feet tall and as it walked away it look like it was "lumbering and kind of hunched over" but was traveling upright on two legs. Spooked the workers walked two miles to their vehicle and drove to the nearest ranger station to stay the night.
Several rangers think what the men heard was nothing more than a mountain lion and that then spooked a bear to rise up on two feet and that is what the men saw.
The lone member of the crew who did not see the figure, but heard it, disagrees. John Davis, a Mono Indian, said he had worked in the mountains for over four decades at the time of the sighting and claims what he heard sounded nothing like a mountain lion. And even though he never saw the figure, he says that the description sounds nothing like that of a bear.
The story doesn't end here though. It seems the original story got the attention of several bigfoot hunters. An unidentified man accompanied by two Dobermans was seen at the Blackrock ranger station informing the rangers that he was there to search for Bigfoot and wanted to know where the crew was currently at. Apparently this was the only sighting of the man. The only other incident regarding a Bigfoot hunter was when a man by the name of Danny Perez who runs at the time a newsletter called BigfooTimes (did a bit of research and he now has a website here) visited the Fresno Bee office looking for directions to the construction site and then soon left. Whether this is the same person who was seen at the Blackrock station was never stated in the article.
Personally I don't think what the men saw was a bear. Yes bears do stand on their hind legs, but I've never heard of one walking on its hind legs for more than a few feet (if I'm wrong someone please correct me). And as for the scream, I'm not sure on that. I know several Bigfoot hunters claim to have the creature's call recorded on audio. But these calls where more of a hoot, similiar to other primate calls. Whether this is the sound the workers heard is hard to say. But what I really find interesting is that the Fresno Bee ran two articles on Bigfoot, one on the sighting itself and the other on the Bigfoot hunters searching for the site. Whatever these men saw, the local newspaper felt it was a big enough story to report on it.
Below are scans of the newspaper articles I was able to get off Google News. Click on them for a larger view.