A police officer directs visitors out of a security line outside the White House in Washington D.C., capital of the United States, April 15, 2013. The White House increased security, and the Justice Department and FBI mobilized to fully investigate the explosions occurring near the Boston Marathon finish line today. (Xinhua/Wang Yiou)
Police officers secure the White House in Washington D.C., capital of the United States, April 15, 2013. The White House increased security, and the Justice Department and FBI mobilized to fully investigate the explosions occurring near the Boston Marathon finish line today. (Xinhua/Zhang Jun)
Police officers secure the White House in Washington D.C., capital of the United States, April 15, 2013. The White House increased security, and the Justice Department and FBI mobilized to fully investigate the explosions occurring near the Boston Marathon finish line today. (Xinhua/Zhang Jun)
A police officer secures the White House in Washington D.C., capital of the United States, April 15, 2013. The White House increased security, and the Justice Department and FBI mobilized to fully investigate the explosions occurring near the Boston Marathon finish line today. (Xinhua/Zhang Jun)
People watch the White House near a cordon outside the building in Washington D.C., capital of the United States, April 15, 2013. The White House increased security, and the Justice Department and FBI mobilized to fully investigate the explosions occurring near the Boston Marathon finish line today. (Xinhua/Zhang Jun)
A police officer secures the White House in Washington D.C., capital of the United States, April 15, 2013. The White House increased security, and the Justice Department and FBI mobilized to fully investigate the explosions occurring near the Boston Marathon finish line today. (Xinhua/Zhang Jun)
Police officers secure the White House in Washington D.C., capital of the United States, April 15, 2013. The White House increased security, and the Justice Department and FBI mobilized to fully investigate the explosions occurring near the Boston Marathon finish line today. (Xinhua/Zhang Jun)