SAN FRANCISCO — A Northern California transit agency on Wednesday released a video recording showing one of its police officer fatally shooting a man fighting with another man.

The 52-second video clip showed Bay Area Rapid Transit officer Joseph Mateu shooting Sahleem Tindle, 28, three times in the back outside an Oakland, California commuter train station. The footage was captured by Mateu’s body camera, which he activated while standing inside the station on Jan. 3.

BART released the clip after several media outlets broadcast a shorter version of the clip posted to the Facebook page of Tindle’s brother. BART police Chief Carl Rojas said the shorter clip was recorded when the Oakland Police showed Tindle’s family the footage. Oakland police are leading the investigation because the shooting occurred on a city sidewalk across the street from a BART station.

The footage starts with Mateu inside the station talking to a woman accused of fare evasion. Two gunshots could be heard, a woman screams and commuters are seen frantically running into the station.

“What happened?” Mateu shouts. Someone responds, “They’re shooting.”

Mateu draws his gun and runs toward the gunfire, shouting several times for directions to the shooting.

After sprinting for about 20 seconds, the officer encounters two men wrestling on a sidewalk.

“Let me see your hands, let me see your hands, both of you, both of you,” he shouts at the men. He screams “Let me see your hands” two more times as he gets within a few feet of the fighting men and then fires three shots in quick succession.

Tindle falls onto his stomach and then rolls over on his back and shows the officer his hands.

BART also released two still images taken from the clip, which the police chief says shows a gun Tindle used to shoot the other man in the leg. A gun was recovered at the scene and can be scene lying on the sidewalk in the video after Tindle is shot.

Tindle’s family has filed a legal claim with BART alleging the officer fired before he determines that Tindle had a gun. If BART denies the claim, the family’s lawyer John Burris said a wrongful death lawsuit will be filed.

Rojas, the transit agency police chief, said the officer acted heroically by running toward gunfire. Mateu has returned to active duty, Rojas said.

Oakland police and the Alameda County district attorney said they are each investigating the shooting and declined further comment.

A shooting nine years ago at another Oakland BART station led to unrest and large demonstrations.

Former BART Officer Johannes Mehserle was sentenced to two years in prison after he was convicted of involuntary manslaughter for fatally shooting Oscar Grant on Jan. 1, 2009, on an Oakland train platform. Mehserle is white; Grant was black and unarmed.

Grant’s story, and the shooting, were the basis for the 2013 film “Fruitvale Station.”