On August 21, 2008, NIST released a draft of its final report on the collapse of 7 World Trade Center. In the report, NIST explains that fire was the main reason for the collapse, along with lack of water to fight the fire. The fire continued to burn throughout the afternoon on the lower floors, and at 5:20 pm. a critical column on the 13th floor buckled and triggered a progressive collapse of the entire structure.
Unlike the Twin Towers, the collapse of 7 WTC had been anticipated for several hours and the building had been evacuated. A transit was used to measure the extent of a visible bulge.