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Boston bombing: ‘Someone knows who did this’

Federal law enforcement authorities have no new leads on who is responsible for what President Obama has called a "act of terrorism" in Boston.

BOSTON - APRIL 15: A woman kneels and prays at the scene of the first explosion on Boylston Street near the finish line of the 117th Boston Marathon on April 15, 2013. (Photo by John Tlumacki/The Boston Globe via Getty Images)
BOSTON – APRIL 15: A woman kneels and prays at the scene of the first explosion on Boylston Street near the finish line of the 117th Boston Marathon on April…

Amanda Sakuma