BATON ROUGE — President Obama said Thursday he had “full confidence” in the Justice’s Department’s ability to conduct a fair investigation in the fatal police shooting death of a black man caught on video in Louisiana this week, saying “we have seen tragedies like this too many times.”

“All of us Americans should be troubled by these shootings, because they are not isolated incidents,” Obama told reporters in Warsaw ahead of a NATO summit. “They’re symptomatic of a broader set of racial disparities that exist in our criminal justice system.”

The encounter between Alton Sterling, 37, and police outside the Triple S Food Mart on Tuesday was captured on cellphone video, and the footage — showing that Sterling was on the ground underneath two officers when he was killed — circulated widely online and has sparked calls for reform in law enforcement.

It came the same week as another fatal police encounter involving a 32-year-old black man in Minnesota. Philando Castile died at a Minneapolis hospital after an officer opened fire during a traffic stop Wednesday. The immediate aftermath of the shooting was captured in a live video streamed on Facebook by a passenger in the car.

A prayer vigil in honor of Alton Sterling was held Thursday night at the Living Faith Christian Center in Baton Rouge.

Louisiana Gov. John Bel Edwards (D) addressed the crowd, praising the citizens of Baton Rouge for their peaceful protests since the shooting, promising a thorough investigation into Sterling’s death, and suggesting renewed methods of improving relations between the community and police.

“We are going to come out this tragedy stronger and more united than ever,” he said.

Edwards praised citizens for their handling of the tragedy thus far. “There were people who felt like they needed to give voice to their anger, to their sadness, to their anxiety,” he said, ” but throughout that process, it remained peaceful, and that is a testament to the people of Baton Rouge.”

“There may be a time for demonstrations, there may be a time for protest, but there is no time for violence,” Edwards told the crowd.

Edwards said an investigation into the incident is already underway, and told the crowd he met Thursday with Louisiana State Police head Mike Edmonson, U.S. Attorney for the Middle District of Louisiana Walt Green, and New Orleans FBI chief Jeffrey Sallet to ensure that all of the resources of the state of Louisiana will be available to investigators.

Sterling’s death has now garnered national attention. Baton Rouge police, the local district attorney, and Edwards, who called the video “disturbing,” announced that federal officials would investigate the death.

Joel Porter, an attorney for Abdullah Muflahi, the owner of the food mart where Tuesday’s shooting occurred, said Thursday that his client was expected to speak with federal investigators.

“Hopefully it will be today,” Porter told The Post. “I don’t know who all the FBI wanted to participate in the interview, but I know they did tell me that there are people from the Justice Department that they wanted to be a part of that interview.”

Porter described the shooting as “a murder, plain and simple.”

“I think that’s the word that should be used,” he said.

Muflahi said he spotted police pulling up Tuesday, and by the time he got outside, officers were already “pushing” on Sterling. Two officers tackled him, and both “got on top of him,” Muflahi said.

“And then that’s when one cop screamed out ‘Gun!’ and then they shot him,” he said.

Muflahi spoke by phone from his store Thursday.

“They’re saying that they they were called because he was out here threatening people with a gun,” Muflahi said of the police. “But I don’t think that was happening at all. I was here the whole night. I had no complaints about him. I didn’t see or hear about him getting into arguments with anybody. I didn’t see him upset or angered by anybody.”

Attorneys representing Quinyetta McMillon, the mother of Sterling’s son, Cameron, and the teen said in a statement that their goal was to “provide this grieving family with the answers they are seeking regarding the senseless shooting death of Alton Sterling.”

“We will demand transparency from the Baton Rouge police department and all other agencies involved in this investigation. We will not stop until every question has been answered,” L. Chris Stewart and Justin Bamberg said in a statement. “We are not here to agitate or incite, but to simply follow the path to justice for this deserving family.”

Stewart previously worked with the family of Walter Scott, a man who was fatally shot by a South Carolina police officer when he fled a traffic stop.

“It’s just sick,” Stewart said in a phone interview Thursday, describing what goes through his mind when watching footage of the Stewart incident. “It’s just such a waste of a life. It’s like he’s not looked at as a human being, but as some type of animal.”

He said he felt police could have deescalated the situation.

“Oh, definitely,” Stewart said. “Come on.”

He called the shooting an example of “what happens when two rogue officers decide to choose violence over talking.”

Sterling is one of more than 120 black Americans shot and killed by police so far in 2016, according to a Washington Post database. About 10 percent of the black Americans shot and killed were unarmed at the time of the shooting, while about 61 percent were armed with a gun.

He is also the second person fatally shot by Baton Rouge police this year. The first was Calvin Smith, a 22-year-old black man who police say led them on a car chase before opening fire, wounding two officers in February.

That shooting happened less than half a mile from where Sterling was shot this week.

Blane Salamoni and Howie Lake II were on Wednesday named as the officers involved in Sterling’s shooting. The gunfire rang out after police responded to a complaint about an armed man threatening people.

CNN, which cited a law enforcement official, reported that a homeless man made the emergency call to local authorities. The official told the news network that Sterling flashed a firearm after the homeless man asked for money.

A second video of the shooting, which surfaced Wednesday, appeared to show an officer taking a gun from Sterling’s pocket after he was shot. Muflahi confirmed that he shot that footage.

Lake is a three-year veteran of the department, and Salamoni is a four-year veteran from a local law enforcement family. Both have been placed on administrative leave.

Lake was among the officers involved in a 2014 shooting, according to Baton Rouge officials. He was placed on leave during an investigation into that shooting, but was cleared and wasn’t disciplined.

The Associated Press on Thursday reported that Lake and Salamoni had faced a four prior complaints about “use of force.” (Each had two.) According to AP, Lake and Salamoni were cleared in all the matters, which involved three black men and a black juvenile.

A search of court records indicates that Sterling had a criminal record, which dated back to the 1990s. That record included aggravated battery, domestic abuse, possessing marijuana with the intent to distribute and illegally carrying a weapon with a controlled dangerous substance.

On Wednesday in Baton Rouge, hundreds gathered throughout the day to share poetry, song, prayer and words as local leaders called on members of the black community to boycott establishments in the city.

Crowds spilled into the street surrounding the food mart where the shooting occurred, and traffic in the area was backed up for blocks. Protesters carried signs and shed tears, but remained peaceful on the hot Louisiana day.

The gathering ended with a vigil for Alton Sterling, led by Democratic state Rep. C. Denise Marcelle, who called speakers to a makeshift stage in the middle of the crowded parking lot.

“Take a moment to remember the last smile, the last conversation, the last encounter you had with him,” Marcelle said, asking for a moment of silence in Sterling’s honor.

At one point on Wednesday, a brass band featuring a cracked white tuba burst into the crowd, followed by jubilant dancers. When the sound began to overpower the speakers, the band moved to a nearby intersection, and much of the crowd poured into the streets in pursuit of the music, still wielding their handmade signs.

The vigil began to wane at that point, but a large crowd remained in the parking lot.

Jaime Triplett, 36, lives just a half block away from the Triple S and said that she knew Sterling well from her visits to the store.

“I say I’m the mother of an endangered species,” she said. “I have two black sons between the ages of 17 and 25.” She bought poster board for her children to create signs, then headed to the scene with her teenage sons early Wednesday.

“I’m glad to see an outpouring of love,” she said of the scene in her neighborhood. “People coming together and standing up for something.”

Larimer reported from Washington. Elahe Izadi contributed to this story, which has been updated.