A man was killed Saturday night after gunshots were fired at a Black Lives Matter protest in Austin, Texas.

A suspect - who witnesses said tried to drive through the crowd of protesters before shooting the victim - was arrested Saturday night and is cooperating with officers, the Austin Police Department said.

The victim was brought to the hospital, where he was pronounced dead. No one else was injured during the incident, authorities said.

The victim was identified by family and friends as Garrett Foster, an Austin resident who was protesting along with his fiancé, Whitney Mitchell, who is a quadruple amputee.

It is not yet clear what led to the shooting, and police have not identified the suspect.

A police official said Saturday that Foster "may have been carrying a rifle and approached suspect vehicle."

The suspect then shot at the victim from his car, the official said.

Shortly before he was killed, journalist Hiram Gilberto Garcia interviewed Foster, who was reportedly carrying an AK-47 rifle. During the interview, Foster said that he began bringing his gun to protests after his roommate was arrested during one of them.

Openly carrying firearms in public places is legal in Texas, as long as it is not done "in a manner calculated to alarm," according to state law.

"They don’t let us march in the streets anymore, so I got to practice some of our rights," Foster said in the interview that was broadcast live on Periscope.

"I mean, if I use it against the cops, I'm dead, and I think all the people that hate us and want to say shit to us are too big of pussies to stop and actually do anything about it," Foster said.

Hours later, the same journalist who interviewed Foster captured footage of the chaotic scene after he was fatally shot, including the sound of several gunshots.

"A car drove up - we were taking the streets - and he shot Garrett," an unnamed protester said in Garcia's video.

The protester said Foster was Mitchell's "caretaker, and has been for like ten years."

A witness, Michael Capochiano, told the New York Times that he saw the suspect's car veer toward the crowd before the shooting, causing people to run away in fear.

“You could hear the wheels squealing from hitting the accelerator so fast,” Capochiano, 53, said. “I’m a little surprised that nobody got hit. He was driving at an aggressive speed into the crowd.”

The driver stopped after hitting a traffic cone, Capochiano said, and many protesters approached the vehicle to yell at him. Foster also approached the car, with his rifle pointing downwards, according to Capochiano.

“He was not aiming the gun or doing anything aggressive with the gun,” Capochiano told the Times. “He was not holding it in an aggressive manner... I’m not sure if there was much of an exchange of words. It wasn’t like there was any sort of verbal altercations. He wasn’t charging at the car. He was just walking over there.”

After Foster's death, protesters gathered to mourn and comfort Mitchell, according to video captured by the Austin Statesman.

"Say his name: Garrett Foster," the protesters chanted, as many hugged Mitchell.

Foster's mother, Sheila Foster, told Good Morning America that her son and Mitchell had been together since they were 17. They attended the protest together, as they had "almost every day for the past 50 days," she said.

Mitchell, who Foster was pushing in her wheelchair at the time of the shooting, was not hurt, she added.

Sheila Foster said her son cared deeply about standing up against police brutality and racism, in part because of his relationship with Mitchell, who is Black.

"He was doing it because he feels really strongly about justice and he’s very heavily against police brutality and he wanted to support his fiancé," she said.

Responding to reports that Foster was armed at the protest, his mother said she thinks that may have been possible.

"It wouldn’t surprise me, because he does have a license to carry, and he would’ve felt the need to protect himself," she said.

A GoFundMe to cover funeral costs for Foster, which was organized by Mitchell's mother, Patricia Kirven, has raised over $40,000.

Foster "fought against injustice, served in the military, and was fiercely protective of his fiancée," Kirven wrote.

"They fell in love at 17 and were never apart," she wrote.