On September 11, 2001, many survivors, firefighters, and first responders described hearing what they called “explosions” throughout the World Trade Center. In the Twin Towers, FDNY transcripts recorded Engine 6 reporting, “There was just a huge explosion,” while Captain John Sudnik recalled “a rush of dust with high pressure coming in with force that I’ve never experienced before.” Dispatchers also reported “major explosions” as the towers burned, and witnesses noted detonations and booms that