Ramzi bin al-Shibh in the context of "Mohamed Atta"

Marwan al-Shehhi (9 May 1978 – 11 September 2001) was an Emirati terrorist hijacker for al-Qaeda. He was the hijacker-pilot on United Airlines Flight 175 (Boeing 767). As part of the September 11 attacks, he crashed the plane into the South Tower of the World Trade Center in a suicide attack. He was one of five hijackers aboard the aircraft and one of two Emiratis to take part in the attacks, the other being Fayez Banihammad, who helped him hijack the same plane.

Al-Shehhi was a university student in applied sciences from the United Arab Emirates. In 1996, at the age of 18, he moved to Germany to pursue his university education. There, he met Mohamed Atta and Ziad Jarrah, who were also studying applied sciences and engineering. Shortly thereafter, Ramzi bin al-Shibh, who provided them with financial support, joined them, and they formed the Hamburg cell. Together, after pledging their lives to martyrdom (Jihad), they became the leaders of the September 11 attacks.

Ziad Samir Jarrah (Arabic: زياد سمير جراح; 11 May 1975 – 11 September 2001), also known as Ziad al-Jarrah, was a Lebanese terrorist who was a member of al-Qaeda, a pan-Islamist militant organization. During the 11 September attacks in 2001, he was one of 19 al-Qaeda members who hijacked four American commercial flights in an attempt to crash them into national landmarks in the country. Jarrah's group hijacked United Airlines Flight 93, departing Newark, New Jersey, for San Francisco, but they failed to reach their target when the plane crashed.

Jarrah grew up in a secular and wealthy family living in Beirut during the Lebanese Civil War (1975-1990). In 1996, he moved to Germany to study aerospace engineering at the Hamburg University of Applied Sciences. In Hamburg, he became part of a clandestine cell system known as the Hamburg cell with fellow hijackers Mohamed Atta and Marwan al-Shehhi, among many others. In 1999, member Ramzi bin al-Shibh took the cell to Afghanistan to meet al-Qaeda's leader, Osama bin Laden, where they were instructed to receive flight training. In 2000, Jarrah enrolled in a flight school in Florida.

The Hamburg cell (German: Hamburger Zelle; Arabic: خلية هامبورغ, Khalia Hamburh) were a clandestine cell system of eleven Islamist terrorists living in Hamburg, Germany, in the late 1990s. In 1999, they traveled to Afghanistan to meet with leaders of the militant organization al-Qaeda, and then returned to Hamburg to work on al-Qaeda's plan for terrorist attacks against the United States. This led to the September 11 attacks in 2001, in which four American airliners were hijacked in an attempt to crash them into important landmarks in the country.

Germany, the U.S., and the United Nations collectively consider eleven people to have been members. Three of them—Mohamed Atta, Marwan al-Shehhi, and Ziad Jarrah—were hijackers of American Airlines Flight 11, United Airlines Flight 175, and United Airlines Flight 93, respectively. In 2002, Ramzi bin al-Shibh stated that only he and those three men were members. However, authorities also list: Abdelghani Mzoudi, Mamoun Darkazanli, Mohammed Haydar Zammar, Mounir el-Motassadeq, Naamen Meziche, Said Bahaji, and Zakariya Essabar.

The al-Quds Mosque (Arabic: مسجد القدس, romanized: Masjid al-Quds, lit. 'The Jerusalem Mosque'; German: al-Quds-Moschee) was a Sunni Islam mosque, located in Hamburg, Germany. The mosque was opened in 1993 and operated until 2010 when it was shut down by German security officials.

The mosque was known for preaching a radical form of Sunni Islam. The al-Quds Mosque was attended by some of the September 11 attackers including Mohamed Atta, Marwan al-Shehhi, Ramzi bin al-Shibh, and Ziad Jarrah who formed the Hamburg cell.