 The bulk of the investigation of 7 World Trade Center was delayed until after reports were completed on the Twin Towers . In the meantime , NIST provided a preliminary report about 7 World Trade Center in June 2004 , and thereafter released occasional updates on the investigation . According to NIST , the investigation of 7 World Trade Center was delayed for a number of reasons , including that NIST staff who had been working on 7 World Trade Center were assigned full @-@ time from June 2004 to September 2005 to work on the investigation of the collapse of the Twin Towers . In June 2007 , Shyam Sunder explained , " We are proceeding as quickly as possible while rigorously testing and evaluating a wide range of scenarios to reach the most definitive conclusion possible . The 7 WTC investigation is in some respects just as challenging , if not more so , than the study of the towers . However , the current study does benefit greatly from the significant technological advances achieved and lessons learned from our work on the towers . " 
