Police are asking for help in investigating an incident in which a man attending a Black Lives Matter protest in Austin, Texas, was fatally shot.

Garrett Foster marched in downtown Austin on Saturday to fight against police violence while pushing his fiancée in a wheelchair, reports The Dallas Morning News. Foster and Whitney Mitchell, a quadruple amputee, had been attending protests in the past few weeks. Foster, a white man, and Mitchell, a Black woman, were passionate about racial equality.

Foster, along with the rest of the demonstrators, was marching down 4th Street and Congress Avenue when a driver turned down the road and started honking their horn. Protesters said that the driver “aggressively accelerated” into the crowd, according to KXAN. 

According to KXAN, the driver stopped, and Foster approached the driver at the window. The driver fired shots, hitting Foster, and then drove away. Another individual in the crowd then began shooting at the car, witnesses told police.

Austin Police Chief Brian Manley said Foster was carrying an AK-style rifle and pointed it at the driver before he was shot, but did not fire any rounds. The driver admitted to shooting at someone who approached their window, according to CBS DFW.

The driver and the person in the crowd who fired their gun have been released from police custody after giving their testimony. They both had a license to carry. It's unclear whether Foster had a license, but according to the Houston Chronicle, Texas allows open carry of long guns without a license.

Manley said that officers were monitoring the protests when they heard two rounds of shots being fired. The driver called 911 and reported the incident. When police arrived at the scene they found Foster with gunshot wounds and attempted to resuscitate him before he was taken to Dell Seton Medical Center. He was pronounced dead at the hospital at 10:25 p.m.

Manley said that witnesses have varying accounts of what occurred.

“Gunshots were fired from inside the vehicle at Mr. Foster,” Manley said. “During the initial investigation of this incident, it appears Mr. Foster may have pointed his rifle at the driver of this vehicle prior to being shot.”

Mitchell’s mother said her daughter is not physically hurt but she is mourning the loss of her fiancé.

“Inconsolable is the only word I can think of because she’ll talk for a bit and then break down,” Patricia Kirven said.

She said she had been worried about the couple attending protests.

“I told her not to go. I was afraid something would happen,” Kirven said. “She said, ‘I don’t feel like I’m doing enough. I want to do more.’“

Garrett’s mom, Sheila Foster, said these issues were important to her son and that he wanted to show solidarity. She said that the two had been attending protests “almost every day for the past 50 days.”

“He was going to these protests because he was fighting against police brutality,” Sheila said. “He was pushing her wheelchair across the intersection when this happened. Thank God she didn’t get hit.”

Sheila said Garrett, who became engaged to Mitchell at 18 after a year of knowing one another, always cared for his partner. After Mitchell came down with an unexpected illness, he came home from the military as soon as possible.

“He’s been doing it ever since,” Sheila said. “He loved that woman unconditionally.”

Kirven doesn’t believe Garrett had approached the driver aggressively. 

“He jumped in front of Whitney and the guy rolled down the window and shot him,” Kirven said, which she was told by the couple’s friends. “They thought the person was aiming at her because she is a sitting duck.”

After the incident, a crowd gathered outside of the Austin Police Department headquarters shouting, “Say his name! Garrett Foster.”

Flowers and signs remembering Garrett were put up in front of the police headquarters and the intersection where he was shot. Many gathered for a vigil on Sunday night to honor him.

Police are reviewing videos of the incident and witness testimonies. They are asking for anyone who may have evidence to turn it over.

“It is important that the community come forward and help us with this investigation,” Manley said.

A GoFundMe campaign to cover Garrett’s funeral and other expenses has raised over $108,000.