Abstract: At approximately 10:00 a.m. on August 1, 2001, Employee #1, a day laborer for UPC Hauling Company, was assigned to cut a large, heavy tree stump at a hillside site in San Francisco, California. Employee #1 was standing at an angle and was using a chain saw to cut the stump when the stump suddenly shifted in the wrong direction and fell toward him. It knocked him down and crushed his left arm against an adjacent shorter stump. Employee #1's arm was almost completely severed by the blow. He was transported to San Francisco General Hospital, where he was admited for treatment. Employee #1 had been hired on the day of the accident and was neither trained nor instructed in the hazards involved in the job assignment. It was recommended that the employer provide safety training that specifically addressed all identified jobsite hazards.