A U.S. flag flies at half-staff at the White House in Washington D.C., Dec. 14, 2012. A tearful President Barack Obama expressed "overwhelming grief" on Friday for the victims of a shooting rampage at Sandy Hook Elementary School and called on Americans to set aside politics and take "meaningful action" to prevent further tragedies of this kind.

A flag at the U.S. Capitol flies at half-staff in honor of the Connecticut school shooting victims in Washington D.C., Dec. 14.

A National Park Service employee lowers flags at the base of the Washington Monument to half-staff after President Barack Obama ordered the action while speaking on the shootings at the Sandy Hook Elementary School on Dec. 14, in Washington, D.C.

An American flag at the center of Newtown, Conn. stands at half-staff on Dec. 14.