US President Barack Obama arrives to speak on economy in the South Court Auditorium of the Eisenhower Executive Office Building, next to the White House, in Washington, DC, on September 16, 2013 to mark the five-year anniversary of the financial crisis. Obama on Monday condemned the "cowardly" shooting at the Washington Navy Yard, and vowed a "seamless" operation to administer justice to those responsible. One gunman was killed and two other potential shooters remain at large, police said, after the attack in the naval installation, just a few miles across Washington from the White House.