Boston Marathon investigators have found a piece of circuit board they believe was part of one of the bombs.

Police and the FBI have raided a number of homes in Boston in the hunt for those responsible for the explosions at the Boston Marathon.

Police are reported to be searching a flat in a Boston suburb as part of the investigation into the explosions near the finish line of the Boston Marathon.

AN early morning shooting in Boston left a toddler and three other people dead, and a fifth person was hospitalised and not expected to survive, police said yesterday.