While drilling the AD, under supervision of the TP inside the drilling console, observed an oil leak on the TDS. The TP called the CM to the rig floor to assess the problem. While the string was still rotating the TP left the Drillers console to join the CM on the rig floor to discuss the source of the leak. The DM joined the discussion. All three (3) were positioned between the TDS and the Drillers side Mast “A:” frame leg (within the Red Zone). Suddenly the pipe handler assembly with the elevator installed to the bails rotated clockwise, crushing the CM him against the Mast “A” frame leg. The DM was struck by the elevators knocking him outward of the pipe setback area. Subsequently the TP was struck by the DM and was pushed towards the Drillers console. The CM succumbed to his injuries while the DM and TP received minor injuries.