Boston has marked the one-year anniversary of the bombing at the U.S. city's annual marathon.
Three people died and more than 260 were injured when twin pressure-cooker bombs detonated at the marathon finish line on April 15, 2013.
President Barack Obama observed the anniversary of the bombing with a moment of silence at the White House.
Vice President Joe Biden was among the dignitaries on hand in Boston to honor victims of the attacks.
A formal flag-raising ceremony and moment of silence took place at the marathon finish line.
Police found two suspicious backpacks hours after the tributes had ended.
One man was taken into custody and a bomb squad blew up both bags "for precautionary reasons," Boston police said on Twitter.
Based on reporting by AP and Reuters