The Hamburg cell was, accoring to U.S. and German intelligence agencies, a group of radical Islamists that included students who eventually came to be key operatives in the 9/11 attacks. Important members included Mohamed Atta al Sayed, who led the four hijacking teams in 2001 and piloted American Airlines Flight 11; Ramzi Binalshibh, who conspired with the other three members but was unable to enter the United States; and Marwan al-Shehhi, who piloted United Airlines Flight 175. Less important members included Said Bahaji, Zakariya Essabar, Mounir el Motassadeq, and Abdelghani Mzoudi. Ziad Jarrah, another prominent 9/11 hijacker, is also sometimes listed in the Hamburg cell.