Six year-old Peter Samuelson wears a firefighter hat after a memorial service at Old St. Pat's Church to mark the tenth anniversary of the September 11 terror attacks on the World Trade Center on September 11, 2011 in New York City. New York City firefighters are commemorating the 10th anniversary of the 9/11 terrorist attacks and honoring the 343 firefighters who died in the line of duty. (Photo by Justin Sullivan/Getty Images)
Memorable moments: Ground Zero memorial ceremony
A collection of moments from the 9/11 anniversary memorial ceremony in New York.