And as Sullivan watched the towers collapse that day, like so many did, he pondered at how fast it all took place, and how suddenly and symmetrically they were brought down. "I knew it was an explosive event as soon as I saw it, there was no question in my mind," said Sullivan. Most of us agree -- it's not by chance that the first tower just happened to collapse -- then the second in the same manner. What convinced him completely is when he watched Tower 7 fall that day, "I mean, come on, it was complete destruction. I've seen buildings fall like that for years -- that was the end game for me." Keep in mind that Sullivan did this for a living for several years -- it is like second nature for him to see this type of demolition. If anybody would know, it should be him. But we went ahead and asked him, “Is there any chance that normal office fires (the official cause of the ’collapse’) could have been responsible for the smooth, symmetrical, free-fall acceleration of building 7? “Not a chance,” he retorted. We just wanted to be sure.