Allen Tannenbaum: First of all, you have to overcome your sense of disbelief that this is happening right here in front of you in New York City. Plus you have to keep yourself safe. And then, in what is really a chaotic and dangerous situation, you have to remember all your camera techniques. I was looking to shoot what I saw, one thing after another. As I moved towards the towers I heard the sound of another plane, a roar of engines, and there was a huge explosion, and the fireball. I was on the north side, just three blocks away, and this huge fireball came out the north side from the impact of the second plane. That was a moment I thought, "This might be my last picture." But after I took a few frames of that explosion I ducked behind a building and debris rained into the street.