These are rare pictures that capture Ground Zero BEFORE the 2nd Tower fell. Bill Biggart gave his life for these pictures. More pictures and info at the link.
"So we track through to the end, and we see the second to the last frame. He is moving forward, he is walking down West street, and he is moving towards the pedestrian overpass connecting the World Trade Center and the World Financial Center. Bill is getting closer and closer, and you see more firemen and fire trucks and the second to the last frame you see policemen, and fire trucks under the overpass.
"And then you see the last frame that nobody else will ever have. You see the honeycomb pieces of the first building... and we see half of the hotel that was destroyed as well. After the second building fell, the hotel, the Marriott I think, was gone. You see it cut in half from what fell from the first building and it is time stamped 10:28 and 24 seconds. Basically that time stamp is the end, because at 10:30 is when the second building came down.
"Bill was killed when the second building came down, and he was crushed under all the debris. I don't know if he jumped back under the underpass, or whether the direct debris killed him. We know in his last picture he was working to the very end, and that's telling of the commitment he had to his work."
http://digitaljournalist.org/issue0111/biggart_intro.htm