A FORMER U.S. Marine dressed in black and carrying extra ammunition shot and killed three law enforcement officers in Baton Rouge, the capital of the southern U.S. state of Louisiana, on Sunday, less than two weeks after a black man was fatally shot by police there in a confrontation that sparked nightly protests that reverberated nationwide.

    Three other officers were wounded, one critically. Police said the gunman was killed at the scene.

    The shooting less than 1.6 kilometers from police headquarters added to the tensions across the country between the black community and police. Just days earlier, one of the slain officers had posted an emotional Facebook message about the challenges of police work in the current environment.

    U.S. President Barack Obama condemned the attack, vowed that justice would be done and called on Americans to focus on rhetoric and actions that united the country rather than divided it.

    “We as a nation have to be loud and clear that nothing justifies violence on law enforcement,” Obama said in televised remarks from the White House.

    The gunman was identified as Gavin Long of Kansas City, who turned 29 Sunday.

    Long, who was black, served in the Marines from 2005 to 2010, reaching the rank of sergeant. He was deployed to Iraq from June 2008 to January 2009, according to military records.

    Although he was believed to be the only person who fired at officers, authorities were investigating whether he had some kind of help.

    While in the military, Long was awarded several medals, including one for good conduct, and received an honorable discharge. His occupational expertise was listed as “data network specialist.”

    The University of Alabama said Long attended classes for one semester in 2012 and university police had no interactions with him.

    It was the fourth high-profile deadly encounter in the United States involving police over the past two weeks. In all, the violence has cost the lives of eight officers, including those in Baton Rouge, and two civilians, and sparked a national debate over race and policing.

    Authorities initially believed that additional assailants might be at large, but hours later said there were no other active shooters. They did not discuss the gunman’s motive or any relationship to the wider police conflicts.

    A witness to Baton Rouge shooting, Brady Vancel, told a CBS television affiliate he had seen a gunman, a second man in a red shirt lying in a parking lot and another gunman running away “as shots were being fired back and forth from several guns.”

    He said the police arrived shortly after the gunfire began.

    Of the two officers who survived the shooting, one was hospitalized in critical condition, and the other was in fair condition. Another officer was being treated for non-life-threatening injuries, hospital officials said.

    Also Sunday, a domestic violence suspect opened fire on a Milwaukee police officer who was sitting in his squad car. The officer was seriously wounded, and the suspect fled and apparently killed himself, authorities said.(SD-Agencies)