No unexploded bombs at Boston Marathon

    BOSTON (AP) — Massachusetts Gov. Deval Patrick says no unexploded bombs were found at the Boston Marathon. He says the only explosives were the ones that went off Monday.
    Three people were killed, including an 8-year-old boy, by two explosions just seconds apart near the finish line.
    Police commissioner Ed Davis says 176 victims came to hospitals around Boston, and 17 of those are in critical condition.
    The two bombs that ripped through the crowds were fashioned out of pressure cookers and packed with shards of metal, nails and ball bearings, a person briefed on the investigation said Tuesday.
    The details on the apparently crude but deadly explosives emerged as investigators appealed to the public for amateur video and photos that might yield clues, and the chief FBI agent in Boston vowed ‘‘we will go to the ends of the Earth’’ to find those responsible.
    Special Agent in Charge Richard DesLauriers says at a news conference there are no known additional threats.
    Police commissioner Ed Davis says it is the most complex crime scene in history of the department.
    Authorities are looking for amateur video and photographic evidence that can give clues to who set off the bombs.
    Suffolk County District Attorney Daniel Conley says ‘‘what occurred in Boston was an act of cowardice.’’