For starters they thought it was dangerous and would collapse:
but also we were pretty sure that 7 World Trade Center would collapse. Early on, we saw a bulge in the southwest corner between floors 10 and 13, and we had put a transit on that and we were pretty sure she was going to collapse. You actually could see there was a visible bulge, it ran up about three floors. It came down about 5 o’clock in the afternoon, but by about 2 o’clock in the afternoon we realized this thing was going to collapse.
http://www.firehouse.com/terrorist/911/magazine/gz/hayden.html So we go there and on the north and east side of 7 it didn’t look like there was any damage at all, but then you looked on the south side of 7 there had to be a hole 20 stories tall in the building, with fire on several floors. Debris was falling down on the building and it didn’t look good.
But they had a hoseline operating. Like I said, it was hitting the sidewalk across the street, but eventually they pulled back too. Then we received an order from Fellini, we’re going to make a move on 7. That was the first time really my stomach tightened up because the building didn’t look good. I was figuring probably the standpipe systems were shot. There was no hydrant pressure. I wasn’t really keen on the idea. Then this other officer I’m standing next to said, that building doesn’t look straight. So I’m standing there. I’m looking at the building. It didn’t look right, but, well, we’ll go in, we’ll see.
http://www.firehouse.com/terrorist/911/magazine/gz/boyle.htmlAlso there was this:
• The building had sustained damage from debris falling into the building, and they were not sure about the structural stability of the building.
• The building had large fires burning on at least six floors. Any one of these six fires would have been considered a large incident during normal FDNY operations.
• There was no water immediately available for fighting the fires.
• They didn’t have equipment, hose, standpipe kits, tools, and enough handie talkies for conducting operations inside the building.
http://wtc.nist.gov/pubs/NISTNCSTAR1-81.pdf page 165
One Battalion Chief coming from the building indicated that they had searched floors 1 through 9 and found that the building was clear.390 In the process of the search, the Battalion Chief met the building’s Fire Safety Director and Deputy Fire Safety Director on the ninth floor. The Fire Safety Director reported
that the building’s floors had been cleared from the top down. By this time, the Chief Officer responsible for WTC 7 reassessed the building again and determined that fires were burning on the following floors:
6, 7, 8, 17, 21, and 30.391 No accurate time is available for these actions during the WTC 7 operations; however, the sequence of event indicates that it occurred during a time period from 12:30 p.m. to
approximately 2:00 p.m.
The Chief Officer then met with his command officer to discuss the building’s condition and FDNY’s capabilities for controlling the building fires. A Deputy Chief who had just returned from inside the
building reported that he had conducted an inspection up to the 7th or 8th floor.392 He indicated that the stairway was filling with smoke and that there was a lot of fire inside the building. The chiefs discussed the situation and the following conditions were identified:
• The building had sustained damage from debris falling into the building, and they were not sure about the structural stability of the building.
• The building had large fires burning on at least six floors. Any one of these six fires would have been considered a large incident during normal FDNY operations.
• There was no water immediately available for fighting the fires.
• They didn’t have equipment, hose, standpipe kits, tools, and enough handie talkies for conducting operations inside the building.
At approximately, 2:30 p.m., FDNY officers decided to completely abandon WTC 7, and the final order was given to evacuate the site around the building. 395, 396 The order terminated the ongoing rescue
operations at WTC 6 and on the rubble pile of WTC 1. Firefighters and other emergency responders were withdrawn from the WTC 7 area, and the building continued to burn. At approximately 5:20 p.m., some three hours after WTC 7 was abandoned the building experienced a catastrophic failure and collapsed.