Dignitaries, including US Vice President Joe Biden, survivors and first responders participate in a flag raising ceremony at the finish line in Boston, Massachusetts April 15, 2014, on the one-year anniversary of the 2013 Boston Marathon bombings. Biden, other leaders and survivors of the Boston Marathon bombing shared messages of thanks and defiance on Tuesday at a tribute to the three people killed and 264 wounded in the attack exactly one year ago. [Photo/Agencies]