Working in the lab, first I heard was when one of the office girls asked me how a plane could hit the WTC. When you fly, you get flying questions. Asked her if it was a small plane and then said it had happened in the past in bad fog when a B-25 hit the Empire State building, but with modern ATC that seemed small chance. Later she came back and said it was a big jet, by then someone had a TV running and the rest was history.