One of the blast sites on Boylston Street near the finish line of the 2013 Boston Marathon is seen in Boston, Tuesday, April 16, 2013, one day after bomb blasts killed three and injured over 140 people. FBI agents searched a suburban Boston apartment overnight and appealed to the public for amateur video and photos that might yield clues to who carried out the Boston Marathon bombing. (AP Photo/Elise Amendola)
One of the blast sites on Boylston Street near the finish line of the 2013 Boston Marathon is seen in Boston, Tuesday, April 16, 2013, one day after bomb blasts killed three and injured over 140 people. FBI agents searched a suburban Boston apartment overnight and appealed to the public for amateur video and photos that might yield clues to who carried out the Boston Marathon bombing. (AP Photo/Elise Amendola)

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, and more than 150 injured by two explosions just seconds apart near the finish line Monday.

Special Agent in Charge Richard DesLauriers says there are no known additional threats and agents are following a number of leads.