The Boston Marathon headquarters has been locked down following two explosions moments ago.

Witnesses said they heard two booms near the finish line inside of the Fairmount Copley Plaza Hotel as people gathered to cheer. There are reports of injuries, but police are unsure how many. Police have now confirmed there was an explosion.

UPDATE: 2:06 MST- Fox News is reporting two people have died and police have found two unexploded device near the scene. Those devices are being dismantled by bomb squads now.

UPDATE: 3:02 P.M. MST - Police have now confirmed a third explosion at JFK Library which may be linked to the Boston Marathon explosions.

UPDATE: 3:19 pm- At a press conference that just concluded, Boston Police Commissioner Ed Davis said that a third explosion, this one at the JFK Library a few miles away from the marathon site, was related to the explosions on Boylston Street. However, the JFK Library is saying that any connection to the first two explosions is “pure speculation,” that everyone is fine and the fire is contained.

UPDATE: 3:51 PM - Police now say explosion at JFK library may have been fire related.