President Obama on Monday ordered flags on all public buildings across the country flown at half-staff to honor the three Louisiana police officers who died and the three others who were wounded during Sunday when a Missouri man ambushed and killed the officers in Baton Rouge.

U.S. flags were already being flown at half-staff to express solidarity with France and honor the 84 people who died in Nice when a terrorist drove his truck into a crowd celebrating Bastille Day last week. He also ordered flags to be flown half-staff starting July 8 in honor of the five police officers who died in Dallas in a sniper ambush.

"As a mark of respect for the victims of the attack on police officers perpetrated on Sunday, July 17, 2016, in Baton Rouge, Louisiana … I hereby order that the flag of the United States shall be flown at half-staff at the White House" and all public buildings and grounds, the president said in a proclamation Monday. The flags will remain at half-staff until Friday night.

The American flag also will fly half staff at all U.S. military posts, naval stations and all naval vessels, embassies, consular offices and facilities abroad.

The slaying of three police officers in Baton Rouge Sunday came during a time when the nation was on high alert after the Dallas attack on law enforcement. The Dallas ambush took place within days of police shooting and killing two black men in Minnesota and Louisiana.

Obama has summoned Attorney General Loretta Lynch and FBI Director James Comey to the White House Tuesday for an impromptu meeting undoubtedly to discuss the increasing threats against law enforcement.

On Sunday, he condemned the violence against law enforcement officers and called on Americans to "temper our words and open our hearts."