It work at my desk. My boss (at the time) was watching CNN in his office while having a coffee, and called me in shortly ofter the first plane struck. While we were watching the second hit. We both said "Bin Laden"?, simultaneously.
What was the most personally frightening thought for me was that my oldest son works in NYC, and took the subway to work about that time of day. His train passed through Penn Station (which was in the basement of the WTC). I called his cell, half not expecting to get an answer because he was on a subway. surprisingly he did answer, and had no clue what was happening.
I told he to get the hell out of there, and get away from the towers. Shortly after that we lost the signal, and I wasn't able to contact him for about 12 hours. When he finally called he told me that he spent the last 11 hours trying to get out of NYC, back to New Jersey, and all cell service was out in the area.
Needless to say it was one of the most welcomed phone calls I ever received.
