Pretty sure I've told this story at least once before, but here goes again...
I was a grad student at UT at the time. I got to the lab I was working in, and everybody was talking about it. No tvs in the lab, so we all went home.
Later that day I got a frantic phone call from my half sister: Her mom (my step mom) was in Manhattan for work. She couldn't get a hold of her on the phone. My father was drunk (as usual) and losing his shit and was talking about driving from Dallas to NY to try and find her. He wanted me to drive to Dallas from Austin to stay with my high school age sister. I talked him out of it, luckily.
I hadn't even known my step mom was in Manhattan.
Much later that day, we finally got a call from my step mom. When the first plane hit, she was in a conference room a few blocks from the trade center in a meeting with a bunch of co-workers, most of whom she hadn't ever met in person. When they heard the explosion, security started yelling to evacuate the building. Then the first building collapsed, and cops yelled for everyone to get back inside. A few minutes later, people who were closer to ground zero started coming into the lobby of her building, completely covered in ash. Looked like ghosts, my step mom said. She ended up walking from lower Manhattan to the train station and took a train to New Jersey. She stayed with a co-worker from their NY office that she had never met before. She never recovered any of her stuff from her hotel room (clothes, credit cards, etc). After about a week, she rented a car and drove back to Dallas. I think she found somebody who was also from Dallas and they shared the ride.
There is more to the story, the long trek through manhattan, the ash and smoke and general chaos, the train ride to New Jersey, staying with complete strangers in a house with two kids, and not even being able to buy a toothbrush (much less clothes that weren't completely covered in ash) until we could get some money sent to her. The PITA of trying to rent a car to get home.
Every year I call her on 9/11. Every year she tells me the same story, and every time she starts to cry when she gets to the part about the people completely covered in ash. Even if I'm talking to her on the phone I can hear her get upset.
One year, my daughter in about 5th grade or so, mentioned that her step grandmother had been in Manhattan on 9/11 to her teacher, and the teacher wanted her to come to the school and tell her story. She didn't want to, said it would be too hard. I really need to record her telling the story, she's in her upper 70s now, and may not be around much longer to tell it.