are you just talking about the two plane crashes?
If so, I remember from the tour I took in NYC at ground zero, pretty much every one that was above the floor that the planes impacted who were still up there, could not get out and perished. Then you need to add in the poor 1st responders and those on the ground that died after the fact. I would gather it would be 1-2k people. They have all the names listed out in the memorial.
I am not sure what you are getting at?