At least three Baton Rouge police officers were killed and three others injured Sunday morning, the city's mayor and the East Baton Rouge Parish Sheriff's Office said.

At least one suspect is dead. Law enforcement officials initially said they believed that two others suspects were at large, but at a news conference Sunday afternoon officials said the deceased suspect was likely the only shooter.

A senior law enforcement official said that suspect wore black fatigues and was armed with a rifle.

By 3 p.m. (CT) Sunday, state police said there was "no active shooter" situation.

The attack comes less than two weeks after the fatal shooting of a black man by police sparked protests in Baton Rouge, turning the city into the latest flashpoint in the ongoing debate over law enforcement tactics.

The officers were responding to a call of shots fired when they were gunned down in an apparent "ambush" around 9 a.m. local time, Baton Rouge Mayor Kip Holden told MSNBC.

Multiple police units were stationed at Our Lady of the Lake Regional Medical Center, where the stricken officers were believed to be undergoing treatment at a trauma center, The Associated Press reported. One of the officers was in critical condition, according to officials.

An AP reporter who was at the scene saw police vehicles with lights flashing massed about a half-mile from the police headquarters on Airline Highway. Police armed with long guns on the road stopped at least two vehicles driving away from the scene and checked their trunks and vehicles before allowing them to drive away, the reporter said.

Marquis Gibson, an eyewitness, was at the Hammond Aire Plaza mall when he heard shots and ran inside. "Officers were falling down and hiding," he told NBC News.

In a statement, President Barack Obama condemned the attack, saying "there is no justification for violence against law enforcement."

"None," he reiterated.

"For the second time in two weeks, police officers who put their lives on the line for ours every day were doing their job when they were killed in a cowardly and reprehensible assault," the president said.

Louisiana Gov. John Bel Edwards condemned the "unspeakable and unjustified attack" on law enforcement:

 In a statement, New Orleans Mayor Mitch Landrieu said his thoughts and prayers were with the officers "targeted in this brazen attack on law enforcement."

Chattanooga's police chief, Fred Fletcher, responded to the police ambush in Baton Rouge on Facebook on Sunday.

"This is a trying and difficult time for law enforcement across our country. I want to assure our great city that the officers of the Chattanooga Police Department - your officers - will continue to place themselves at risk to stand between violence and our community and that we will do all we can to protect your officers," Fletcher said.

Baton Rouge has been roiled by protests since white officers shot and killed Alton Sterling, a 37-year-old black man, on July 5. Four people were arrested last week in an alleged plot to kill police officers, and a fifth was arrested Saturday.

Nationwide protests erupted following Sterling's death and the killing of another black man, Philando Castile, at the hands of a police officer in Minnesota. At one such protest in Dallas, a sniper opened fire on police officers, killing five and injuring more.