Complicating matters, two of the three stairwells in each tower did not bring people out to the street, but actually deposited them in the mezzanine lobby, which was “a major building design flaw,” Chief Donald Burns of the Fire Department had noted in a report about the 1993 bombing. These exits to the mezzanine required people to get on escalators to bring them to the street level, causing backups in the stairwells that stretched tens of floors up.
