BATON ROUGE, La. (AP) -- Three Baton Rouge law enforcement officers investigating a report of a man with an assault rifle were killed Sunday, less than two weeks after a black man was fatally shot by police here in a confrontation that sparked nightly protests that reverberated nationwide.
Three other officers were wounded, one critically. Police said the suspect was killed at the scene. The dead gunman was believed to be the only person who fired at officers, but authorities were unsure whether he had some kind of help, a state police spokesman said.
"We are not ready to say he acted alone," Major Doug Cain said. Two "persons of interests" were detained in the nearby town of Addis.
The shooting -- which took place just before 9 a.m., less than a mile from police headquarters -- came amid escalating tensions across the country between the black community and police. The races of the suspect and the officers were not immediately known.
It was the fourth high-profile deadly encounter in the United States involving police over the past two weeks. The violence has left 12 people dead, including eight police officers, and sparked a national debate over race and policing.
President Barack Obama urged Americans to tamp down inflammatory words and actions.
"We as a nation have to be loud and clear that nothing justifies attacks on law enforcement," Obama said in remarks from the White House. "Every one right now focus on words and actions that can unite this country rather than divide it further."
Authorities initially believed that other assailants might be at large, but hours later said that no other active shooters were on the loose. They did not discuss the gunman's motive or any relationship to the wider police conflicts.
The shooting began at a gas station on Airline Highway. According to radio traffic, Baton Rouge police answered a report of a man with an assault rifle and were met by gunfire. For several long minutes, they did not know where it was coming from.
The radio exchanges were made public Sunday by the website Broadcastify.
Nearly 2½ minutes after the first report of an officer getting shot, an officer on the scene is heard saying police do not know the shooter's location.
Almost six minutes pass after the first shots are reported before police say they have determined the shooter's location. About 30 seconds later, someone says shots are still being fired.
The recording lasts about 17 minutes and includes urgent calls for an armored personnel carrier called a BearCat.
A law enforcement official familiar with the investigation said the shooter was identified as Gavin Long but had no details. The official spoke on condition of anonymity because the official was not authorized to discuss an ongoing investigation.
In Kansas City, police converged on a house that was listed for a Gavin Long. Some officers had weapons drawn from behind trees. Others took cover behind cars.
Gov. John Bel Edwards rushed to the hospital where the officers were taken. They were from the Baton Rouge Police Department and the East Baton Rouge Sheriff's Office.
"There simply is no place for more violence," Edwards said. "That doesn't help anyone. It doesn't further the conversation. It doesn't address any injustice perceived or real. It is just an injustice in and of itself."
A witness told television station WAFB that he saw a masked man in black shorts and shirt running from the scene where the three officers were killed.
Brady Vancel said the man looked like a pedestrian running with a rifle in his hand, rather than someone trained to move with a rifle.
Vancel said he had gone to work on a flooring job near the gas station when he heard semi-automatic gunfire and perhaps a handgun. He saw a man in a red shirt lying in an empty parking lot and "another gunman running away as more shots were being fired back and forth from several guns."
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.
Each of the officers was married and had a family, East Baton Rouge Parish Sheriff Sid Gautreaux said.
The Baton Rouge attack unfolded hours after a domestic violence suspect opened fire early Sunday 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.
Police-community relations in Baton Rouge have been especially tense since the death of 37-year-old Alton Sterling, a black man killed by white officers July 5 after a scuffle at a convenience store. The killing was captured on widely circulated cellphone video.
It was followed a day later by the shooting death of another black man in Minnesota, whose girlfriend livestreamed the aftermath of his death on Facebook. The next day, a black gunman in Dallas opened fire on police at a protest about the police shootings, killing five officers and heightening tensions even further.
Thousands of people have protested Sterling's death, and Baton Rouge police arrested more than 200 demonstrators.
Sterling's nephew condemned the killing of the three Baton Rouge officers. Terrance Carter spoke Sunday to The Associated Press by telephone, saying the family just wants peace.
"My uncle wouldn't want this," Carter said. "He wasn't this type of man.
A few yards from a police roadblock on Airline Highway, Keimani Gardner was in the parking lot of a warehouse store that would ordinarily be bustling on a Sunday afternoon. He and his girlfriend both work there. But the store was closed because of the shooting.
"It's crazy. ... I understand some people feel like enough is enough with, you know, the black community being shot," said Gardner, an African-American. "But honestly, you can't solve violence with violence."
Michelle Rogers and her husband drove near the shooting scene, but were blocked at an intersection closed by police.
"I can't explain what brought us here," she said. "We just said a prayer in the car for the families."
Associated Press Writer Eric Tucker in Washington contributed to this report.