President Barack Obama has paid tribute to Ambassador Chris Stevens and three others killed in the assault on the U.S. compound in Libya, calling them patriots who served America's ideals -- and laid down their lives for others.

Obama took part in a transfer of remains ceremony in a hangar at Andrews Air Force Base, joined by Vice President Joe Biden and Secretary of State Hillary Rodham Clinton.

After meeting with families of the victims, Obama watched as flag-draped cases containing the remains were carried off of a transport plane and loaded into four black hearses.

Also killed in the Tuesday assault were Americans Sean Smith, Glen A. Doherty and Tyrone S. Woods.

Obama vowed to bring those responsible to justice -- and "stand fast" against attacks on U.S. embassies.

(Copyright 2012 by The Associated Press. All Rights Reserved.)