Obama observed a moment of silence in honour of the victims of the Boston Marathon bombings in the White House on Tuesday, exactly a week after the twin bombs went off.
The event was held in Boston and was attended by the city Mayor Thomas Menino, and the Massachusetts Governor Deval Patrick.
The moments of silence were followed by the ringing of bells throughout the city and the country.
The New York Stock Exchange went silent as well, so did the Senate.
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