Apparently one of them lived in Hamburg, Germany. His name was Mohammed Atta and he is believed to have taken over one of the planes which crashed into the World Trade Center. This is what a German newspaper is reporting right now.
I´ve seen reports on TV as well. From what I picked up, there were two of them and they underwent flight training in the USA from summer 2000 until early 2001.
Here's a link about the ongoing investigation. http://www.cnn.com/2001/US/09/12/investigation.terrorism/
