President Obama, first lady Michelle Obama, Vice President Joe Biden and others observe a moment of silence on the South Lawn of the White House on Thursday to mark the 13th anniversary of the Sept. 11 attacks.
Family members of victims of the Sept. 11 attacks demonstrate against the decision to transfer the unidentified remains to a repository at the World Trade Center site.
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A woman looks out at One World Trade Center from inside the 9/11 Empty Sky memorial at Liberty State Park in Jersey City, N.J., on Wednesday. Americans commemorated the 12th anniversary of the Sept. 11 attacks with solemn ceremonies and pledges to not forget the nearly 3,000 people killed.
Singer Patti LaBelle performs during the "Concert For Hope" event, hosted by Washington National Cathedral, to mark the tenth anniversary of the 9/11 terrorist attacks.
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Keri McMorrow, 7, visits the memorial pool where her uncle's name is engraved, during tenth anniversary ceremonies of the September 11, 2001 terrorist attacks at the World Trade Center site.