President Barack Obama has ordered flags at the White House and all government buildings to be flown at half-staff in honor of the Boston Marathon explosion victims.

Obama signed a proclamation making the order Tuesday morning, calling it a �mark of respect for the victims of the senseless acts of violence� perpetrated in Boston the previous day. He ordered flags to remain lowered through sunset Saturday.

Three people were killed, including an 8-year-old boy, and more than 170 were wounded in Monday�s bombing at the famous marathon�s finish line.

(AP)