Abstract: On May 2, 2003, Employees #1, #2, and #3 had installed the first twenty of approximately fifty-six trusses with three rows of 25.5-in. by 2-in. by 4-in. blocks attached to each truss on the east side of top chord and four rows of the same type of blocking on the west side. Each truss measured approximately 69 ft on the bottom chords and 36 ft on the top chords with a slope of 3 to 12. The bottom cords were 2 in. by 10 in. and the top chords were 2 in. by 8 in. with the webbing being 2 in. by 4 in. According to the truss specifications provided by the truss manufacturer, each truss weighed 635 lb. At the time of the incident, Employees #1, #2, and #3 were on the trusses and another employee was standing on the existing roof. The lead carpenter and another carpenter had installed some permanent bracing and were in the process of installing the temporary bracing consisting of 8 in. and 16 ft by 2 in. by 4in. Employee #2 was assisting by providing material to the other two employees. The three employees were positioned on the third truss working their way from north to south. The top chord of the third truss was bowed and the two employees were trying to straighten it so the bracing could be installed. The carpenter was pushing on the top chord and the lead carpenter was pulling on it. Both stated that they heard the wood break and the truss they were working on broke and started to lean bringing the seventeen trusses with it. As the angle of lean increased the speed of the collapse also increased. As the trusses collapsed Employee #2 was able to grab the existing roof and hang there until another employee pulled him up. Employees #1, #3, and trusses fell 16 ft to the concrete slab. Employees #1 and #3 were flown and the Employee #2 was taken by ambulance to Shock Trauma hospital. One of the employees was treated for fracture and Employee #2 was treated for lacerations. Both of these employees were released from the hospital after treatment. Employee #3 was hospitalized.