Robert Peraza, who lost his son Robert David Peraza, pauses at his son's name at the North Pool of the 9/11 Memorial at the site of the World Trade Center. Justin Lane/pool/Getty Images hide caption

itoggle caption Justin Lane/pool/Getty Images

The "Tribute in Light" illuminates the sky in New York on the 10th anniversary of the Sept. 11 attacks. Timothy A. Clary/AFP/Getty Images hide caption

itoggle caption Timothy A. Clary/AFP/Getty Images