The jet fuel from the boeing 757 causing a destructive inferno that led to the structural breakdown of a portion of the large concrete building. All in all 125 military personnel and civilians were killed in the Pentagon with 64 people aboard the airliner. In less than 15 minutes after World Trade Center collapsed in a massive cloud of dust and smoke. The steel of the skyscraper built to withstand winds of 200 miles per hour and a big conventional fire, could not resist with the tremendous heat generated by the burning jet fuel. The north building at 10:30 a.m of the twin towers collapses. When that happened only six people in the World Trade Center towers at the time of the collapse