It was another deadly day for police in America. Three law enforcement officers were killed and three more were injured in a firefight with a gunman in Baton Rouge, Louisiana, on Sunday morning — the second incident in two weeks to leave multiple cops fatally shot.

The shooting began after officers responded to a call of an armed man dressed in black fatigues near a shopping plaza less than a mile away from the city’s police headquarters. Officers engaged the suspect, who returned fire. Video posted on social media shows a chaotic scene as police scrambled to locate the shooter and bullets flew overhead. After a six-minute gunfight, police radioed that the suspect had been killed.

The shooting is certain to heighten already strained relations between police and some residents in Baton Rouge, the site of daily protests since July 5, when police were videotaped fatally shooting Alton Sterling, a 37-year-old black man, in the chest.

That shooting, and the death of Philando Castile, a 32-year-old black Minnesota man shot by a police officer during a traffic stop the following day, sparked a national outcry and protests.

The slain Louisiana officers have been identified as Brad Garafola, an East Baton Rouge Parish sheriff’s deputy, and Matthew Gerald and Montrell Jackson, of the Baton Rouge Police Department.

Two weeks before he was killed in the line of duty, Jackson, a 10-year veteran of the force, had reflected on social media about the protests that had roiled his community.

“I’ve experienced so much in my short life and the past 3 days have tested me to the core,” he wrote on Facebook. “I swear to God I love this city but I wonder if this city loves me. In uniform I get nasty hateful looks and out of uniform some consider me a threat.”

President Barack Obama condemned the killings in Baton Rouge, urging the public to “be loud and clear that nothing justifies violence against law enforcement.”

While dozens of people are shot and killed every day in the U.S., the intentional targeting of police officers is fairly rare. On July 7, an Army reservist opened fire on law enforcement during a demonstration against police brutality in Dallas. Five officers were killed, and seven wounded. Before he was killed by police, the Dallas gunman told negotiators that he was angry about the recent spate of police shootings and was targeting white officers.

Family members of Alton Sterling, who was buried on Sunday, decried the shooting of the Louisiana police officers. “We are disgusted by the despicable act of violence,” said Quinyetta McMillon, the mother of Sterling’s son, Cameron, in a statement.

This is a developing story, but here is what we know so far:

The gunman was a Marine veteran with reported ties to anti-government groups.

The suspect was identified as Gavin Long, 29, a resident of Kansas City, Missouri. The shooting took place on Long’s birthday.

The New York Times reports that Long Joined the Marines in 2005, and had served a six-month tour in Iraq. He had risen to the rank of sergeant.

The Wall Street Journal reports that Long was affiliated with an anti-government group.

State and local authorities declined to link the shooting to the recent police shootings of black men.

The gunman used a rifle, though the exact model is unknown.

In one of the first police radio dispatches from the scene, an officer reported that a “lady came up and said there was a suspect walking with a [unintelligible] and an assault rifle out here behind the store.”

However, authorities have not commented on the exact model of the rifle. It is unknown if the weapon is in fact an assault weapon — which is designed for fully automatic or burst firing modes — or assault-style, which tend to have military-inspired cosmetic features but are semiautomatic.

An open carrier got caught up in the aftermath.

On Sunday afternoon, police detained a man at Our Lady of the Lake Hospital. He was soon released. Speaking to reporters, a woman who claimed to be the man’s mother said that he was sick and was heading to the emergency room for treatment. He was also openly carrying a handgun, which prompted officers to respond.

The incident was reminiscent of what happened in the aftermath of the police shooting in Dallas on July 7, when police released an image of a man openly carrying a rifle and named him as a “person of interest.” The man, who was a legal gun owner, turned himself over to authorities and was quickly released.

Law enforcement officers across the country have been grappling with open carry as it becomes more popular. Dallas Police Chief David Brown said that police response to the attack on his officers was complicated by the presence of openly carried weapons.

Speaking to CNN, Lieutenant General Russel Honoré, who coordinated military relief efforts following Hurricane Katrina, described open carry as “absolutely crazy.” He added: “This crazy idea you can carry a gun anywhere, anytime, this open carry, has got police on full alert.”

Last summer, in the wake the movie theater shooting in Lafayette, Louisiana, Honoré urged America to “rethink and re-set our thoughts about guns,” in an interview with the Daily Advertiser.

“As a country we’re in a state of denial because we’ve confused the right to bear arms with the right to carry arms all the time anywhere or any place you want,” he said. “We have to have a different kind of conversation in America and be prepared to speak about the politically unspeakable.”

Shortly after the shooting, the Cleveland Police Union called for an open carry ban during this week’s GOP convention.

In the hours after the shooting, Cleveland Police Union President Stephen Loomis said he would be asking Ohio Governor John Kasich to temporarily ban open carry in the city during this week’s Republican National Convention. Loomis called open carry, which is legal in 45 states, “absolute insanity.” “I don’t care if it’s constitutional or not at this point,” he said on CNN.

Open carry advocates have stated their intention to hold demonstrations at the four-day event, sparking fears of violence and confusion for law enforcement tasked with controlling the crowd.

Kasich denied the request in a statement, saying that officials can’t “arbitrarily suspend federal and state constitutional rights or state laws as suggested.”

The shooting comes as police departments increase security measures to protect their officers.

The shooting in Dallas prompted several police departments to increase security for officers. Police in New York, Boston, and Chicago ordered patrols to be conducted in pairs, and on Sunday afternoon, New Orleans police officers were told to partner up in squad cars.

The Cleveland police union also called for officers to work in teams of three at some intersections during this week’s convention.

Shortly after two New York City police officers were ambushed in their squad car and fatally shot in 2014, the Houston Police Officers Union renewed a call to patrol in pairs — a move the organization’s president acknowledged would lower response times for thefts and other low-priority calls.

Fatal shootings of police officers are surging in 2016.

So far this year, 31 officers have died in firearm-related incidents, an increase of 72 percent over the same period last year, according to the National Law Enforcement Officers Memorial Fund.

Including the fatalities in Baton Rouge, seven police officers have been fatally shot in Louisiana this year.

The last Baton Rouge police officer to die in the line of duty before Sunday was Terry Lee Melancon, who was fatally shot while executing a search warrant at the home of a drug dealer on on August 10, 2005.

According to a University of Illinois study released last August, police officers in states with higher rates of gun ownership are three times more likely to be killed on the job. Louisiana is one of the country’s most heavily armed states, with 15.1 guns for every 1,000 residents.

As The Trace reported last year, the state experienced both the most overall gun deaths per capita and the most gun homicides per capita of any state between 2004 and 2013, according to data from the Centers for Disease Control and Prevention. Louisianans were killed by guns at a rate nearly twice that of the national average.

[Photo: Sean Gardner/Getty Images]