I was in the lab when it came on the radio, that a plane had crashed into one of the towers - someone said it was a fighter plane and an accident. Someone else I worked with said 'we should rebuild the tower out of Palestinian bones' not politically correct at all.
One of my relatives in New York didn't go into work in one of the towers that morning because of child care arrangements - and missed the whole thing luckily. Another was climbing the stairs out of the subway when tower 1 was coming down and legged it. Life is precious, you really have to appreciate that.
I also came through Logan Airport two years previously, and the security was shockingly poor - so no surprise that several of the attackers used it as a point of entry.