SHANKSVILLE, Pennsyl. (CBSNewYork/AP) — President Barack Obama says the nation will never forget the lives of those killed in the Sept. 11 attacks.

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Obama said at a Pentagon memorial service that he is inspired by the resilience of the victims’ families. He quoted Scripture: “Let not steadfast love and faithfulness forsake you. Write them on the table of your heart.”

Obama also praised America’s diversity and urged Americans not to let their enemies divide them. He called the day “difficult” but one that “reveals the love and faithfulness in your hearts and in the heart of our nation.”

At the White House, Obama observed a moment of silence at 8:46 a.m. EDT — the time the first hijacked airplane hit the north tower of New York City’s World Trade Center.

Hundreds also gathered for the 9/11 anniversary observance in Pennsylvania where one of the planes hijacked by terrorists crashed in a field 15 years ago.

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They gathered at Flight 93 National Memorial in Shanksville as ceremonies were also taking place Sunday in New York and at the Pentagon. Forty passengers and crew members died in the Pennsylvania crash.

For the first time, the Shanksville ceremony is being held outside the visitor center that opened last year rather than at the granite mall that runs along the crash site. The names of the victims will be read and bells ring in their memory.

The United Airlines flight was heading from Newark, New Jersey to San Francisco when it crashed after passengers and crew members fought the terrorists for control of the plane.

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