NEW YORK ( CNN ) -- Three 60-foot steel beams fell 40 stories at the World Trade Center construction site Thursday after a crane cable snapped . Authorities said no one was injured when the beams -- each weighing several tons -- came hurtling down from one of the new towers being built at the site of the September 11 , 2001 , terrorist attacks . `` The cable of a crane broke , causing the steel it was lifting to fall approximately 40 stories back onto the flatbed truck that had transported the steel into the World Trade Center site , '' said a statement from John Gallagher , spokesman for Tishman Construction , which manages the site . `` The incident occurred within an enclosed section of the site , which is not accessible to the public . '' The 72-story building , which will face the World Trade Center memorial park honoring the victims of 9/11 , is scheduled to officially open in the fall of 2013 , according to the World Trade Center website . `` Fortunately ... nobody was hurt , '' New York Mayor Michael Bloomberg said at a news conference Thursday . Gallagher said in his statement that the construction company was `` investigating the matter in full cooperation '' with authorities including the New York fire department , the Port Authority of New York and New Jersey and the city 's Department of Buildings . `` The job is partially shut down pending the investigation , '' Gallagher said .
Three steel beams fall after a crane cable snaps . The collapse of the bridge was caused by an electrical fault in one of its support cables that snapped and sent two concrete columns plummeting to their deaths.