Leneal Frazier died on Tuesday night during a high-speed crash involving a Minnesota police officer, his family told US media.
A suspect believed to have committed an armed robbery drove away from the crash which killed Mr Frazier and injured an officer.
In a Facebook post, his niece Darnella Frazier said: “I honestly can’t believe I’m making this post right now. I’m so hurt.
“Another Black man lost his life in the hands of the police.”
Mr Frazier’s family told US media he had been near his girlfriend’s house when a police squad car crashed into his Jeep at a crossing.
It is believed police were chasing another car driven by a suspected armed robber when the crash happened.
Police Department spokesman John Elder told the Minneapolis Star Tribune three vehicles were involved in the crash and that an officer suffered minor injuries but did not confirm if Mr Frazier was a victim.
A GoFundMe page has been set up to raise money for Mr Frazier’s funeral.
“Leneal was killed Tuesday, July 6th, 2021 at the intersection of 41st Avenue North and Lyndale Avenue after being struck during a police chase,” the page read.
“The person police were chasing got away, and Laneal who was driving a different car was killed.”
Last month Darnella Frazier was awarded a Pulitzer Prize for filming Minneapolis police officer Derek Chauvin kneeling on Mr Floyd’s neck on May 25 2020.
The video, which was live-streamed and shared around the world, showed the unarmed man saying he could not breathe 27 times before dying.
The prize committee said Ms Frazier, who was aged 17 at the time, had “courageously reported the murder of George Floyd, [in] a video that spurred protests against police brutality around the world, highlighting the crucial role of citizens in journalists’ quest for truth and justice.”