Abstract: On March 13, 1987, three employees were cutting and removing a section of concrete slab flooring in a paper mill. The section being removed was approximately 30 ft by 10 ft with a thickness of 8 inches. Due to the paper machine being located on the floor and being kept in operation during this process, the work being done by the three employees was being done from below or under the floor being removed. The employees were cutting, coring and removing this 30 ft by 10 ft section in approximately 6 ft by 4 ft sections. Ten of these sections had been successfully removed prior to the accident. During the removal of the last two sections, an unplanned collapse occurred resulting in approximately a 6 ft by 10 ft section of floor slab falling and striking the three employees working below it. The three employees were on scaffolding or a staging work platform. It is possible that this accident occurred during the process of removing the ceiling jacks or braces and installation of the forklift unit which was being used to remove sections. Employee #1 was seriously injured sustaining a severely broken left leg and right ankle. Employee #2 sustained minor bruises and a broken rib as he pushed Employee #3 clear of the falling slab. Causal factors included lack of written demolition plan, lack of adequate underpinning and possible lack of adequate supervision on site at the time of the accident. Also, a lack of rebar at the breaking point of the concrete slab was found.