In pictures: The U.S. commemorates the 25th anniversary of 9/11
On Sept. 11, 2001, hijackers flew planes into the World Trade Center and the Pentagon, killing thousands. Photos capture those marking the 25th anniversary.
TL;DR
- Terrorists backed by al-Qaeda hijacked four airliners on Sept. 11, 2001.
- Two planes hit the World Trade Center, one hit the Pentagon, and a fourth crashed in Pennsylvania.
- The attacks killed 2,977 people and led to the U.S. invasions of Afghanistan and Iraq.
- Americans are commemorating the 25th anniversary with ceremonies at ground zero, the Pentagon, and Shanksville.
- Former presidents and current officials attended memorial events.