"Shortly after 9 o'clock ... [Albert Turi the Chief of Safety for the New York Fire Department] received word of the possibility of a secondary device, that is another bomb going off. He tried to get his men out as quickly as he could, but he said there was another explosion which took place, and then an hour after the first hit - the first crash that took place - he said there was another explosion that took place in one of the towers here, so obviously according to his theory he thinks that there were actually devices that were planted in the building.
One of the secondary devices he thinks that took place after the initial impact he thinks may have been on the plane that crashed into one of the towers. The second device - he thinks, he speculates - was probably planted in the building. ... But the bottom line is that he, Albert Turi, said that he probably lost a great many men in those secondary explosions, and he said that there were literally hundreds, if not thousands, of people in those towers when the explosions took place."