 Mechanical equipment was installed on floors four through seven , including 12 transformers on the 5th floor . Several emergency generators installed in the building were used by the Office of Emergency Management , Salomon Smith Barney , and other tenants . In order to supply the generators , 24 @,@ 000 gallons ( 91 @,@ 000 L ) of diesel fuel were stored below ground level . Diesel fuel distribution components were located at ground level , up to the ninth floor . After the World Trade Center bombings of February 26 , 1993 , New York City mayor Rudy Giuliani decided to situate the emergency command center and associated fuel tanks at 7 World Trade Center . Although this decision was criticized in light of the events of 9 / 11 , the fuel in the building is today not believed to have contributed to the collapse of the building . The roof of the building included a small west penthouse and a larger east mechanical penthouse . 
