Abstract: Employees #1 and #2, of Accu-Cut, Inc., were standing on wooden planks laid over a concrete floor slab on the mezzanine of an old trolley building being renovated as an artist's studio. The slab was 15 ft 5 in. above the concrete deck. The employees were using a hand-held concrete saw to cut the slab into squares and a sledge hammer to knock them out. Eventually the whole slab dislodged from the I-beams supporting it, and spilled the employees to the deck. The slab then landed on end and flipped over onto the employees. The slab came to rest on top of the concrete saw, which prevented Employees #1 and #2 from being crushed, but pinned them for several hours. Employees #1 and #2 were hospitalized with serious injuries.