I woke up at the usual time, 6:30am, to catch the opening of the stock market. When I turned the TV on, I was greeted by the sight of smoke coming out of one of the towers. The CNBC newscasters didn't seem to know much about what had caused the fire – they thought it was a small plane but didn't have much more information. So I thought this was either an accident or someone had intentionally crashed into the tower (perhaps a suicide), but didn't immediately think of terrorism. So I figured I'd go out to get some donuts and there would be more news when I got back.
I had the news on while I was out driving, but there wasn't much information beyond what had already been reported. So when I arrived home I turned CNBC on again and saw the tower was still smoking. The reporters had started to discuss the possibility of terrorism, when the second tower was hit. Both towers were ablaze, and it was pretty clear that something serious had happened. There were reporters on the ground (outside the NYSE) covering the event, when both towers fell. One of them saw what happened, screamed "Oh my God!" and took off (along with everyone else). The cameras showed people fleeing from the falling debris.
When I got to work about an hour later (1070 Arastradero in PA), people were talking about what had happened. At that time, my boss (who also graduated from Stuy) asked me if I had any relatives who worked in or near the WTC. I told him my sister worked in midtown NYC, far from the attack, so I figured she would be ok. (I found out later that she was let out of work early, but walked home, because the subways were halted.) There was various talk of terrorist attacks, and looking at logs to see what types of attack-related queries were being made. (I vaguely recall variations on [Osama bin Laden] occurred fairly frequently.) I think we were allowed to go home early that day, but I stayed a little later just to keep an eye on things and see if there were any new developments.
That's about all I remember offhand. The other (sad) news of the day was that layoffs had been announced, but were postponed to give people some time to recover from the impact of the attacks.