| Name | Age | Sex | Injuries | Injured areas |
|---|---|---|---|---|
| Day, Chris | Not recorded | Male | Bruises | Not recorded |
| Webber (Wagner), Bob | Not recorded | Male | Bruises | Not recorded |
| Britain, Keith | Not recorded | Male | Head injury | Head |
| Hedlund, Ellis | Not recorded | Male | Bruises | Not recorded |
The dig site has an opening composed of large rocks wedged in above the entrance. A 25-foot deep shaft at a 50° angle intersects a small passage at the bottom of the shaft. On Memorial Day weekend five cavers intended to continue digging in search of more cave passage. At about 12:45 p.m. four people had entered the shaft. Chris Day, the fifth man, was just beginning to enter. As he shifted positions, he touched a rock level with his head. The rock, which weighed approximately 200 pounds and was roughly 1 1/2 feet on a side and 8 inches thick, immediately fell from the ceiling without warning. It struck Day's left foot, dropped 12 feet vertically, and then bounced another 15 feet, hitting several times in the small shaft. Because of the suddenness, no one had time to shout "rock." Bob Webber (or Bob Wagner) was hit next. It struck the right side of his hard hat, splitting it, and then hit both his knees. The rock then bounced off the foot wall of the shaft about 7 feet from the bottom. It hit Keith Britain on the left side of his head knocking him against the wall and knocking off his hard hat. Finally the rock landed on the hips and legs of Ellis Hedlund who was halfway into the crawl at the bottom. Dan Dubrall was not injured since he had already gone down to the first chamber. Dubrall and Britain first removed the rock from Hedlund who had been pinned by it. Day, Webber, and Hedlund all suffered from moderate bruises but were able to climb out unaided; however Britain had been seriously cut by the rock. He was observed to be stunned, conscious, and coherent, but was bleeding from the nose and cuts above his left eye and the left side of the head. He was given aid in getting out of the cave. Help was obtained from other caving parties in Lilburn Cave. Britain was given first aid but developed nausea and shock. He was taken by Jeep to the Grant Grove Ranger Station and then immediately to the Valley Medical Center of Fresno.
Analysis: The rock had been in position for two winters since the dig was started and was occasionally used as a hand hold in entering and exiting the cave. It was part of the overhanging lip of the entrance and had been carefully inspected the previous year although not recently. Especially around digs, potentially loose rocks should be checked and removed regularly. Two hard hats were smashed. A hard hat with a crushable liner might have reduced Britain's head injury. The cavers should have entered the shaft one at a time in order to minimize the chance of multiple injury from falling rocks.