PHOTOS: Remembering the terrorist attacks of 9/11

At least 1,000 family members, survivors, rescuers and officials were gathered as the ceremony at the World Trade Center began with a moment of silence and tolling bells. Then, relatives began reading out the names of the nearly 3,000 people killed when terrorist-piloted planes hit the trade center, the Pentagon and a Pennsylvania field, hurling America into a new consciousness of the threat of global terrorism.

(Carmen Taylor / Associated Press)

United Airlines Flight 175 flies into the South Tower at 9:03 a.m. on Tuesday, Sept. 11, 2001.

(Det. Greg Semendinger / NYPD)

A damaged tower collapses.

(Thomas E. Franklin / Associated Press)

Firefighters raise a flag late in the afternoon of Sept. 11, 2001, in the wreckage of the World Trade Center towers.

(Gulnara Samoilova / Associated Press)

People covered in dust walk over debris near the World Trade Center in New York.

(RICHARD DREW / Associated Press)

A person jumps from the burning North Tower of the World Trade Center as another clings to the outside, left center.

(Daniel Hulshizer / Associated Press)

Thick smoke billows behind the Statue of Liberty from where the towers once stood.

(Alex Fuchs / Associated Press)

The remains of the World Trade Center.

(Suzanne Plunkett / Associated Press)

People flee as a World Trade Center tower collapses behind them.

(Hubert Michael Boesl / AFP/Getty Images)

Smoke billows from the top floors of the World Trade Center towers.

(Seth Wenig / Associated Press)

Flowers cover the names of the victims of the 9/11 terrorist attacks before a ceremony at Ground Zero in New York on Monday.