Atlanta's police chief resigned on Saturday hours after a black man was fatally shot by an officer in a struggle following a field sobriety test. Authorities said the slain man had grabbed an officer's Taser, but was running away when he was shot.

Police chief Erika Shields stepped down as the killing of 27-year-old Rayshard Brooks sparked a new wave of protests in Atlanta after turbulent demonstrations that followed the death of George Floyd in Minneapolis had simmered down.

Protesters on Saturday night set fire to the Wendy's restaurant where Brooks was fatally shot the night before and blocked traffic on a nearby highway.

Atlanta Mayor Keisha Lance Bottoms announced the police chief's resignation at a Saturday afternoon news conference. The mayor also called for the immediate firing of the unidentified officer who opened fire at Brooks.

'I do not believe that this was a justified use of deadly force and have called for the immediate termination of the officer,' Bottoms said.

She said it was Shields' own decision to step aside as police chief and that she would remain with the city in an undetermined role. Interim corrections chief Rodney Bryant would serve as interim police chief until a permanent replacement is found.

The Georgia Bureau of Investigation, which is investigating the shooting, said the deadly confrontation started with officers responding to a complaint that a man was sleeping in a car blocking the restaurant's drive-thru lane. The GBI said Brooks failed a field sobriety test and then resisted officers' attempts to arrest him.

The GBI released security camera video of the shooting Saturday. The footage shows a man running from two white police officers as he raises a hand, which is holding some type of object, toward an officer a few steps behind him. The officer draws his gun and fires as the man keeps running, then falls to the ground in the parking lot.

GBI Director Vic Reynolds said Brooks had grabbed a taser from one of the officers and appeared to point it at the officer as he fled, prompting the officer to reach for his gun and fire an estimated three shots.

The security camera video recorded Brooks 'running or fleeing from Atlanta police officers,' Reynolds said. 'It appears that he has in his hand a Taser.'

The footage does not show Brooks' initial struggle with police.

L. Chris Stewart, an attorney for Brooks' family, said the officer who shot him should be charged for 'an unjustified use of deadly force, which equals murder.'

'You can't have it both ways in law enforcement,' Stewart said. 'You can't say a Taser is a nonlethal weapon ... but when an African American grabs it and runs with it, now it's some kind of deadly, lethal weapon that calls for you to unload on somebody.'

He said Brooks was a father of four and had celebrated a daughter's eighth birthday Friday before he was killed.

The shooting came at a time of heightened tension over police brutality and calls for reforms across the U.S. following the May 25 death of Floyd in Minneapolis. Atlanta was among U.S. cities where large crowds of protesters took to the streets.

Demonstrators, including members of Brooks' family, gathered Saturday outside the restaurant where he was shot.

Among those protesting was Crystal Brooks, who said she is Rayshard Brooks' sister-in-law.

'He wasn't causing anyone any harm,' she said. 'The police went up to the car and even though the car was parked they pulled him out of the car and started tussling with him.'

She added: 'He did grab the Taser, but he just grabbed the Taser and ran.'

Shields, Atlanta's police chief for less than four years, was initially praised in the days following Floyd's death last month. She said the Minnesota officers involved should go to prison and walked into crowds of protesters in downtown Atlanta, telling demonstrators she understood their frustrations and fears. She appeared at Bottoms' side as the mayor made an impassioned plea for protesters to go home when things turned violent with smashed storefronts and police cruisers set ablaze.

Days later, Shields fired two officers and benched three others caught on video May 30 in a hostile confrontation with two college students whose car was stuck in traffic caused by the protests. The officers fired Tasers at the pair and dragged them from the vehicle. When prosecutors later charged six of the officers involved, however, Shields openly questioned the charges.

The shooting of Brooks two weeks later raised further questions about the Atlanta department. In a statement, Shields said she chose to resign 'out of a deep and abiding love for this city and this department.'

'It is time for the city to move forward and build trust between law enforcement and the communities they serve,' Shields said.

Reynolds said his agents will turn over results of their investigation to Fulton County District Attorney Paul Howard, whose office will decide whether criminal charges are warranted against either of the unidentified officers.

Howard said Saturday his office 'has already launched an intense, independent investigation of the incident' without waiting for the GBI's results.

Brooks died after being taken to an Atlanta hospital. One of the officers was treated and released for unspecified injuries.

The Associated Press