<p>Bill Iffrig, 78, lies on the ground as police officers react to a second explosion at the finish line of the Boston Marathon, April 15, 2013. Iffrig, of Lake Stevens, Wash., was running his third Boston Marathon and near the finish line when he was knocked down by one of the two bomb blasts. (Photo: John Tlumacki/Boston Globe via Getty Images) </p>
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