10 years later: Remembering 9/11 at ground zero

Robert Peraza, who lost his son Robert David Peraza, pauses at his son's name at the North Pool of the 9/11 Memorial during tenth anniversary ceremonies at the site of the World Trade Center on Sept. 11, 2011, in New York City. New York City and the nation are commemorating the 10th anniversary of the 9/11 terrorist attacks on lower Manhattan which resulted in the deaths of 2,753 people after two hijacked planes crashed into the World Trade Center. Security has been heightened in both New York City and Washington D.C. following a possible car bomb threat.

Complete coverage: 9/11 anniversary

Credit: Justin Lane-Pool/Getty Images