One of the things I remember about the day was how the initial reports were wildly inaccurate. The first information I got, from a work colleague, was that New York was on fire after a massive plane accident, and that over 30,000 people had been killed. I was very sceptical, and thought it must be a hoax, especially when she told me that the WTC had collapsed. I had been to the observation deck there a few years before and I didn't think it was possible that a building that massive could collapse.
I drove home and watched mesmerised at the footage of the planes hitting the towers. The reports of the falling bodies was just ghastly.
Growing up in the UK in the 1970s, it seemed like there were terrorist bombings and shootings every week (mainly connected to the IRA). And of course, globally, there are terrorist atrocities on a vast scale every year. Yet 9/11 did feel different to me; I guess my main reaction was one of apprehension as to what was going to happen next. We had a 17 year old Russian student stopping with us at the time; quite presciently, he pointed out that it was going to be treated like an act of war rather than act of criminality.