<h3> Based on its comprehensive investigation, NIST concluded that the WTC towers collapsed because: (1) the impact of the planes severed and damaged support columns, dislodged fireproofing insulation coating the steel floor trusses and steel columns, and widely dispersed jet fuel over multiple floors; No one escaped at or above the impact point in the North Tower. Clark's testimony before the 9/11 Commission, where he detailed problems with the 911 emergency call system, has been widely quoted.</h3>
