New York Firefighter heroes state what many others have claimed. There were secondary explosions in the World Trade Centers before they collapsed. The Sears Tower was hit in the 1970′s by an airplane and burned for HOURS, but of course did not just crumble to dust. There obviously had to be other sources of trauma to the building’s structure. Also, World Trade Center 7 was NEVER HIT by and airplane or any extreme debris, but did house many important government offices. World Trade Center Building 7 crumbled to dust at free fall speeds later in the day on 9/11/01.