Pennsylvania 9/11 anniversary

La-Shawn Clark, left, and Mark Cannizzaro read names of victims of the Sept. 11 attacks during a ceremony marking the 17th anniversary on Tuesday, Sept. 11, 2018, in New York. Clark lost her husband, Benjamin Clark, and Cannizzaro lost his cousin, Brian Cannizzaro.

A woman leaves flowers at the North Pool during a ceremony marking the 17th anniversary of the terrorist attacks on the United States on Tuesday, Sept. 11, 2018, in New York.

Family members of Flight 93 victims listen during the September 11th Flight 93 Memorial Service, Tuesday, Sept. 11, 2018, in Shanksville, Pa.

Audience members listen during the September 11th Flight 93 Memorial Service, Tuesday, Sept. 11, 2018, in Shanksville, Pa.

A member of the military walks the grounds of the National 9/11 Pentagon Memorial before the start of the September 11th Pentagon Memorial Observance at the Pentagon on the 17th anniversary of the September 11th attacks, Tuesday, Sept. 11, 2018.

Visitors to the Flight 93 National Memorial in Shanksville, Pa., participate in a sunset memorial service on Sept. 10, 2018, as the nation marks the 17th anniversary of the Sept. 11, 2001 attacks.

Visitors to the Flight 93 National Memorial in Shanksville, Pa., participate in a sunset memorial service on Sept. 10, 2018, as the nation marks the 17th anniversary of the Sept. 11, 2001 attacks.

Visitors to the Flight 93 National Memorial in Shanksville, Pa., participate in a sunset memorial service on Sept. 10, 2018, as the nation marks the 17th anniversary of the Sept. 11, 2001 attacks.

Visitors to the Flight 93 National Memorial in Shanksville, Pa., view the Wall of Names on on Sept. 10, 2018, as the nation marks the 17th anniversary of the Sept. 11, 2001 attacks.

This Tower of Voices Flight 93 National Memorial in Shanksville, Pa., pictured here on Sept. 9, 2018.

This Tower of Voices Flight 93 National Memorial in Shanksville, Pa., pictured here on Sept. 10, 2018.