 In May 2002 , the Federal Emergency Management Agency ( FEMA ) issued a report on the collapse based on a preliminary investigation conducted jointly with the Structural Engineering Institute of the American Society of Civil Engineers under leadership of Dr. W. Gene Corley , P.E. FEMA made preliminary findings that the collapse was not primarily caused by actual impact damage from the collapse of 1 WTC and 2 WTC but by fires on multiple stories ignited by debris from the other two towers that continued burning unabated due to lack of water for sprinklers or manual firefighting . The report did not reach conclusions about the cause of the collapse and called for further investigation . 
