President Barack Obama ordered White House flags and all flags at federal facilities to half-staff Tuesday to honor the four U.S. Marines and one Navy sailor killed last week in the attack in Chattanooga.

“Our thoughts and prayers as a Nation are with the service members killed last week in Chattanooga. We honor their service. We offer our gratitude to the police officers and first responders who stopped the rampage and saved lives,” Obama said in the proclamation ordering the flag to half-staff.

“We draw strength from yet another American community that has come together with an unmistakable message to those who would try and do us harm: We do not give in to fear. You cannot divide us. And you will not change our way of life”.

The flags should remain at half-staff until sunset Saturday, according to the presidential proclamation.

Obama called the five service members “heroes” during a speech Tuesday in Pittsburgh. He mentioned the names of the four U.S. Marines and one Navy sailor killed in the attack: Gunnery Sgt. Thomas J. Sullivan; Sgt. Carson A. Holmquist; Lance Cpl. Squire “Skip” K. Wells; Staff Sgt. David A. Wyatt; and U.S. Navy sailor Randall Smith.