According to the Los Angeles County Fire Department, the incident was reported around 1:52 p.m. after a male hiker fell into a ravine. The LA County Sheriff's Department later confirmed that the hiker had died.
Heart attack and subsequent fall. SAR is guarding the person until coroner can get there or until he says bring the body down to him at/near the trailhead. Location is above First Water where there are fixed ropes to help navigate the trail through a narrow rocky/ledgy portion.