There were visible fires on at least 14 floors in WTC 7, according to the NIST report. There may also have been fires on other floors that weren't visible because of the smoke. Some quotes that show the severity of the fires:
Chief of Operations Daniel Nigro:
"The biggest decision we had to make was to clear the area and create a collapse zone around the severely damaged [WTC 7] building. A number of fire officers and companies assessed the damage to the building. The appraisals indicated that the building’s integrity was in serious doubt." Fire Engineering magazine, 10/2002]
In another interview, Chief Nigro says,
"The most important operational decision to be made that afternoon was [that] the collapse [Of the WTC towers] had damaged 7 World Trade Center, which is about a 50 story building, at Vesey between West Broadway and Washington Street.
It had very heavy fire on many floors and I ordered the evacuation of an area sufficient around to protect our members, so we had to give up some rescue operations that were going on at the time and back the people away far enough so that if 7 World Trade did collapse, we [wouldn't] lose any more people. We continued to operate on what we could from that distance and approximately an hour and a half after that order was [given], at 5:30 in the afternoon, 7 World Trade Center collapsed completely."
http://tinyurl.com/g8c6y
When the building came down it was
completely involved in fire, all forty-seven stories.
–FDNY Assistant Chief Harry Myers (Smith, Dennis, 2002. Report From Ground Zero: The Heroic Story of the Rescuers at the World Trade Center. New York: Penguin Putnam. p. 160)
We walked over by number Seven World Trade Center as it was burning and saw this
40-plus story building with fire on nearly all floors. –FDNY Lieutenant Robert LaRocca
http://graphics8.nytimes.com/package...IC/9110081.PDF
...Just when you thought it was over, you're walking by this building and you're hearing this building creak and
fully involved in flames. It's like, is it coming down next? Sure enough, about a half an hour later it came down. –FDNY Lieutenant James McGlynn
http://graphics8.nytimes.com/package...IC/9110447.PDF
I walked out and I got to Vesey and West, where I reported to Frank [Cruthers]. He said, we’re moving the command post over this way, that building’s coming down. At this point, the
fire was going virtually on every floor, heavy fire and smoke that really wasn’t bothering us when we were searching because it was being pushed southeast and we were a little bit west of that.
http://www.firehouse.com/terrorist/9.../visconti.html
All morning I was watching 7 World Trade burn, which we couldn't do anything about because it was so much chaos looking for missing members. –Firefighter Marcel Klaes
http://graphics8.nytimes.com/package...IC/9110018.PDF
The concern there again, it was later in the afternoon, 2, 2:30, like I said. The fear then was Seven.
Seven was free burning. Search had been made of 7 already from what they said so they had us back up to that point where we were waiting for 7 to come down to operate from the north back down. –Captain Robert Sohmer
http://graphics8.nytimes.com/package...IC/9110472.PDF
Then we had to move because the Duane Reade, they said, wasn't safe because building
7 was really roaring. –FDNY Chief Medical Officer Kerry Kelly.
http://graphics8.nytimes.com/package...IC/9110207.PDF
At this point
Seven World Trade was going heavy, and they weren't letting anybody get too close. Everybody was expecting that to come down. –Firefighter Vincent Massa
http://graphics8.nytimes.com/package...IC/9110222.PDF
Building #7 was still
actively burning and at that time we were advised by a NYFD Chief that building #7 was burning out of control and imminent collapse was probable. –PAPD P.O. Edward McQuade
http://www.thememoryhole.org/911/pa-...-reports02.pdf page 48.
At Vesey St. and West St., I could see that
7 WTC was ablaze and damaged, along with other buildings.
–M. DeFilippis, PAPD P.O.
http://www.thememoryhole.org/911/pa-...-reports03.pdf page 49
[Note: the fires in 7 were probably not mainly due to damage from the south tower, but from the north.]
So yeah then we just stayed on Vesey until building Seven came down. There was nothing we could do.
The flames were coming out of every window of that building from the explosion of the south tower. So then building Seven came down. When that started coming down you heard that pancaking sound again everyone jumped up and starts.
Q: Why was building Seven on fire? Was that flaming debris from tower two, from tower two that fell onto that building and lit it on fire?
A: Correct. Because
it really got going, that building Seven, saw it late in the day and like the first Seven floors were on fire. It looked like heavy fire on seven floors. It was fully engulfed, that whole building. There were pieces of tower two [sic: he probably means tower one] in building Seven and the corners of the building missing and whatnot. But just looking up at it from ground level however many stories -- it was 40 some odd -- you could see the flames going straight through from one side of the building to the other, that’s an entire block. –Firefighter Tiernach Cassidy
http://graphics8.nytimes.com/package...IC/9110413.PDF
"And there's so little they can do to try to fight the fires in these buildings, because
the fires are so massive. And so much of the buildings continues to fall into the street. When you're down there, Dan, you hear smaller secondary explosions going off every 15 or 20 minutes, and so it's an extremely dangerous place to be."
–CBS-TV News Reporter Vince DeMentri
http://terrorize.dk/911/witnesses/91...explosions.wmv
Well, they said
that's (7) fully involved at this time. This was a fully involved building. I said, all right, they're not coming for us for a while. Now you're trapped in this rubble, and you're trying to get a grasp of an idea of what's going on there. I heard on the handy talky that we are now fighting a 40-story building fully involved.
...And
7 World Trade was burning up at the time. We could see it. ... the fire at 7 World Trade was working its way from the front of the building northbound to the back of the building. There was no way there could be water put on it, because there was no water in the area. –Firefighter Eugene Kelty Jr.
http://graphics8.nytimes.com/package...IC/9110261.PDF
The time was approximately 11a.m. Both of the WTC towers were collapsed and the streets were covered with debris. Building #7 was still standing but burning. ...We spoke to with a FDNY Chief who has his men holed up in the US Post Office building. He informed us that the
fires in building 7 were uncontrollable and that its collapse was imminent. There were no fires inside the loading dock (of 7) at this time but we could hear explosions deep inside. –PAPD P.O. William Connors
http://www.thememoryhole.org/911/pa-...-reports04.pdf page 69
"There's number Seven World Trade. That's the OEM bunker." We had a snicker about that. We looked over, and it's
engulfed in flames and starting to collapse.
We're kind of caught in traffic and people and things, and everything's going on. We hear over the fire portable, "Everybody evacuate the site. It's going to collapse." Mark Steffens starts yelling, "Get out of here! Get out of here! Get out of here! We've got to go! We've got to go! It's going to collapse." I turned around, and I piped up real loud and said, "Stay in the frigging car. Roll the windows up. It's pancake collapsing. We'll be fine. The debris will quit and the cloud will come through. Just stay in the car." We pulled the car over, turned around and just watched it pancake. We had a dust cloud but nothing like it was before. –Paramedic Louis Cook
http://graphics8.nytimes.com/package...IC/9110103.PDF
Building 7 fire makes rescuer of NT stairwell victim’s route impassable (just before collapse):
I remember it was bad and I'm going to get to a point where we came back that way on the way up. We couldn't even go that way,
that's how bad the fire was, but by the time I was coming back it was rolling, more than a couple of floors, just fully involved, rolling.
...So now it's us 4 and we are walking towards it and I remember it would have at one point been an easier path to go towards our right, but being building 7 -- that must have been building 7 I'm guessing with that fire, we decided to stay away from that because things were just crackling, falling and whatnot.
...He had called me and said “Hey Jerry don’t try and get back out the way you went in which was big heads up move because he said that building was rolling on top of the building that we were passing. That building was on fire and likely to collapse more too. –Firefighter Gerard Suden
http://graphics8.nytimes.com/package...IC/9110022.PDF
I remember Chief Hayden saying to me, "We have a six-story building over there, a seven-story building, fully involved." At that time he said, "
7 has got fire on several floors." He said, "We've got a ten-story over there, another ten-story over there, a six-story over there, a 13-story over there." He just looked at me and said, "**** 'em all. Let 'em burn." He said, "Just tell the guys to keep looking for guys. Just keep looking for the brothers. We've got people trapped. We've got to get them out." –Lieutenant William Ryan
http://graphics8.nytimes.com/package...IC/9110117.PDF
I walked around the building to get back to the command post and that's when they were waiting for 7 World Trade Center to come down. ...They had three floors of fire on three separate floors, probably 10, 11 and 15
it looked like, just burning merrily. It was pretty amazing, you know, it's the afternoon in lower Manhattan, a major high-rise is burning, and they said 'we know.' –FDNY Chief Thomas McCarthy
http://graphics8.nytimes.com/package...IC/9110055.PDF
There were hundreds of firefighters waiting to -- they were waiting for 7 World Trade Center to come down as it was on fire. It was too dangerous to go in and fight the fire. –Assistant Commissioner James Drury
http://graphics8.nytimes.com/package...IC/9110098.PDF
My first thoughts when I came down a little further into the site, south of Chambers Street, was, "Where am I?" I didn't recognize it. Obviously, the towers were gone. The only thing that remained standing was a section of the Vista Hotel. Building 7 was on fire. That was ready to come down. –Charlie Vitchers, Ground Zero Superintendent
http://www.pbs.org/americarebuilds/p...itchers_t.html