These are truly remarkable testimonies, describing "popping sounds" associated with "red and orange flashings going around the building", "explosions and material shooting out of the building" and then a delay before the collapse. The witnesses state they believed it was a “controlled demolition.”
Sources: The New York Times, San Francisco Chronicle
Stephen Gregory, Assistant Commissioner (F.D.N.Y.)
The testimony of Stephen Gregory, Assistant Commissioner (F.D.N.Y.) (see pp. 14-15 of PDF file for below quotes):
A. ...I thought that when I looked in the direction of the Trade Center before it came down, before No. 2 came down, that I saw low-level flashes. In my conversation with Lieutenant Evangelista, never mentioning this to him, he questioned me and asked me if I saw low-level flashes in front of the building, and I agreed with him because I thought -- at that time I didn't know what it was. I mean, it could have been the result of the building collapsing, things exploding, but I saw a flash flash flash and then it looked like the building came down.
Q. Was that on the lower level of the building or up where the fire was?
A. No, the lower level of the building. You know like when they demolish a building, how when they blow up a building, when it falls down? That's what I thought I saw. And I didn't broach the topic to him, but he asked me. He said I don't know if I'm crazy, but I just wanted to ask you because you were standing right next to me… He said did you see any flashes? I said, yes, well, I thought it was just me. He said no, I saw them, too.
Q. On the television pictures it appeared as well, before the first collapse, that there was an explosion on the upper floors.
A. I know about the explosion on the upper floors. This was like eye level.
Chief Frank Cruthers
The testimony of Chief Frank Cruthers (see page 4 of PDF file for below quote):
"And while I was still in that immediate area, the south tower, 2 World Trade Center, there was what appeared to be at first an explosion. It appeared at the very top, simultaneously from all four sides, materials shot out horizontally. And then there seemed to be a momentary delay before you could see the beginning of the collapse."
The testimony of Daniel Rivera (Paramedic, EMS) (see page 9 of PDF file for below quote):
"It was a frigging noise. At first I thought it was -- do you ever see professional demolition where they set the charges on certain floors and then you hear "Pop, pop, pop, pop, pop" That's exactly what -- because I thought it was that. When I heard that frigging noise, that's when I saw the building coming down."
The testimony of Captain Captain Karin Deshore of emergency medical services (see page 15 of PDF file for below quote):
"Somewhere around the middle of the world trade center there was this orange and red flash coming out. Initially it was just one flash. Then this flash just kept popping all the way around the building and that building had started to explode. The popping sound, and with each popping sound it was initially an orange and then red flash came out of the building and then it would just go all around the building on both sides as far as I could see. These popping sounds and the explosions were getting bigger, going both up and down and then all around the building.
I went inside and told everybody that the other building or there was an explosion occuring up there and I said I think we have another major explosion. I don't know if we are all going to be safe here."