President Obama has ordered flags at the White House and all federal buildings be flown at half-staff in honor of the victims of the Boston bombing.

The president issued a proclamation this morning that all flags be lowered until sunset on April 20 "as a mark of respect for the victims of the senseless acts of violence perpetrated on April 15, 2013, in Boston, Massachusetts."

Flags flying above U.S. embassies and military bases abroad will also fly at half-staff during this duration.

As the flag above 1600 Pennsylvania was lowered, the president was in the West Wing receiving a briefing from his Assistant for Homeland Security and Counterterrorism Lisa Monaco, FBI Director Robert Mueller and other senior members of his team on the recovery effort and ongoing investigation into the attack.