10 years later: Remembering 9/11 at the Pentagon

Retired Air Force Staff Sgt. Alicia Watkins of Washington, D.C., places a Purple Heart medal next to the name of her friend, Army Sgt. Tamara Thurman, on the bronze plaque commemorating the victims of the Sept. 11 Pentagon terror attacks on Sept. 11, 2011. Watkins said she feels "a tremendous amount of guilt" that she survived the attack on the Pentagon when Thurman did not.

A young woman grieves during the 10th anniversary commemorative ceremony of the September 11 attacks at the Pentagon in Washington, Sept. 11, 2011.

President Barack Obama and first lady Michelle Obama lay a wreath as the 10th anniversary of the September 11 attacks are observed at the Pentagon in Washington, Sept. 11, 2011. At right is Chairman of the Joint Chiefs of Staff Adm. Mike Mullen.

An honor guard plays Taps at the the Pentagon Memorial as the 10th anniversary of the September 11 attacks are observed at the Pentagon in Washington, Sept. 11, 2011.

A Secret Service counter-sniper team looks out from atop the flag-draped Pentagon during a 10th anniversary remembrance ceremony at the Pentagon Memorial in Washington on Sept. 11, 2011.

Defense Secretary Leon Panetta, left, and Vice President Joe Biden attend a 10th anniversary remembrance ceremony of the 2001 terror attacks, at the Pentagon Memorial in Washington on Sept. 11, 2011.

People listen during the national anthem at a memorial service at the Pentagon Sept. 11, 2011, in Washington, D.C.

A mourner grieves during the 10th anniversary commemorative ceremony of the Sept. 11 attacks at the Pentagon in Washington, Sept. 11, 2011.

An unidentified man participates in the commemorative ceremony of the Sept. 11 attacks at the Pentagon in Washington, on Sept. 11, 2011.

Families and survivors honor the victims of the the Sept. 11, 2001, attack on the Pentagon at a 10th anniversary remembrance ceremony at the Pentagon Memorial in Washington, Sept. 11, 2011.

A woman lays a sunflower on a bench as the 10th anniversary of the September 11 attacks are observed at the Pentagon in Washington, Sept. 11, 2011.

Soldiers lay wreaths for each Sept. 11 victim on the at the Pentagon Memorial benches bearing their names during the observance 10th anniversary of the Sept. 11 attacks at the Pentagon in Washington, Sept. 11, 2011.

Former Defense Secretary Donald Rumsfeld poses for a photo with people attending the 10th anniversary remembrance ceremony at the Pentagon, in Washington, Sept. 11, 2011.

People recite the Pledge of Allegiance during a memorial service at the Pentagon in Washington on Sept. 11, 2011.