I was attending a class at Houston Community College. The class was about to end, when one of the other instructors came into the room to announce what had happened and to let us know that classes were canceled for the rest of the day.
The idea of two commercial airplanes flying into a building was so bizarre that I actually had to ask her, "Are you talking about a movie?" before I understood that it was real. It seemed like such a crazy incident that only Hollywood could have come up with it.