SEPT. 11, 2015: The sun rises, as One World Trade Center, center left, stands on the 14th anniversary of the Sept. 11, 2001 terrorist attacks. Victims' relatives began marking the 14th anniversary of Sept. 11 in a subdued gathering Friday at ground zero, with a moment of silence and somber reading of names.

SEPT. 11, 2001: The remains of the World Trade Center stands amid the debris following the terrorist attack on the building in New York.

SEPT. 11, 2015: At the Pentagon Memorial a K-9 officer pauses as he looks toward the U.S. flag as it is draped on the side of the Pentagon where the building was attacked.

SEPT. 11, 2001: Fire burns the remains of a car near the Pentagon after the government building was attacked by terrorists on Sept. 11, 2001.

SEPT. 11, 2015: A flag is placed along the South Pool prior to a ceremony at the World Trade Center site in New York.

SEPT. 11, 2001: Fire and smoke billows from the north tower of New York's World Trade Center after terrorists crashed two hijacked airliners into the World Trade Center and brought down the twin 110-story towers.

SEPT. 11, 2015: Souvenirs for 9/11 victims are seen in a memorial across from New York's Lower Manhattan and One World Trade Center in Exchange Place, New Jersey. An overcast Friday greeted relatives who gathered to commemorate nearly 3,000 people killed in the September 11 attacks in New York, Pennsylvania and outside Washington.

SEPT. 11, 2001: People flee the falling South Tower of the World Trade Center.

SEPT. 11, 2015: Members of the Red White and Blue team run through the 9/11 Empty Sky memorial at sunrise across from New York's Lower Manhattan and One World Trade Center, in Liberty State Park in Jersey City, New Jersey. Relatives of the nearly 3,000 people killed in the Sept. 11, 2001, attacks gathered in New York, Pennsylvania and outside Washington to mark the 14th anniversary of the hijacked airliner strikes carried out by al Qaeda militants.

SEPT. 11, 2001: Women wearing dust masks flee across the Brooklyn Bridge from Manhattan to Brooklyn following the collapse of both World Trade Center towers in New York. The towers previously loomed tall in the skyline behind.

SEPT. 11, 2015: Army Sgt. Edwin Morales prays during a ceremony at the World Trade Center site in New York. With a moment of silence and somber reading of names, victims' relatives marked the 14th anniversary of Sept. 11 in a subdued gathering Friday at ground zero.

SEPT. 11, 2001: Firefighters wear masks as they rest among soot and debris near the site of the World Trade Center towers.

SEPT. 11, 2015: A pedestrian walks past flags carrying the names of the victims of the Sept. 11 attacks in Omaha, Neb. The flags were placed at Memorial Park as a tribute to the fallen.

SEPT. 11, 2001: An American flag hangs in front of broken windows in New York.

SEPT. 11, 2015: A runner stops to take a photograph of names on the "Empty Sky" memorial to New Jersey's victims of the Sept. 11, 2001 terrorist attacks.

SEPT. 11, 2001: Dust and debris cloud the air near the site of the terrorist attack on the World Trade Center in New York.

SEPT. 11, 2015: Retired New York City firefighter Joseph McCormick visits the South Pool prior to a ceremony at the World Trade Center site.

SEPT. 11, 2001: With the skeleton of the World Trade Center twin towers in the background, New York City firefighters work amid debris on Cortlandt St.