Explosion below the building before the plane hit

9/11 survivor: there was an explosion prior to plane’s impact
Russia Today - Friday, Sept 11th, 2009

A loud bang shook the building and shortly afterwards the plane hit the skyscraper, states survivor William Rodriguez, who was a janitor in the North Tower of the WTC and helped to rescue others after the planes hit

On September 11, 2001, he was in the basement of the North Tower of the WTC and says before the plane hit there was a huge explosion coming from below, so loud and so high that it pushed those present upwards into the air.