NEW YORK - SEPTEMBER 11: Presidential candidates Sen. Barack Obama and John McCain greet emergency responders Ground Zero on the 7th anniversary of the 9/11 terrorist attacks September 11, 2008 in New York City. Obama and Republican U.S presidential nominee Sen. John McCain (R-AZ) visited the World Trade Center area together to pay tribute to the more than 2,700 people killed on September 11, 2001.