A US police officer who fatally shot young black man during a traffic stop in Minnesota has been charged with second-degree manslaughter.

If found guilty over the death of 20-year-old Daunte Wright, Kim Potter, a 26-year veteran who resigned from the police force on Tuesday, faces up to 10 years in prison and a US$20,000 fine.

Mr Wright was shot after being pulled over for what police said was an expired car registration, and officers discovered there was a warrant out for his arrest.

Potter was taken into custody on Wednesday morning and is being held in Hennepin County jail without bail over the shooting, which has sparked days of unrest in Minneapolis.

Former Brooklyn Centre police chief Tim Gannon said Potter accidentally drew her pistol instead of her Taser during a struggle with Mr Wright, who got back into his car.

In body camera video of the incident, Potter can be heard shouting “I’ll Tase you! I’ll Tase you! Taser! Taser! Taser!” before firing a shot from her handgun.

To be convicted under Minnesota law, prosecutors must show that Potter was “culpably negligent” and took an “unreasonable risk” in her actions against Mr Wright.

People watch body cam video showing the moment Daunte Wright was shot. Photo: Getty

Cases of officers mistakenly firing their gun instead of a Taser do happen, but experts say they are extremely rare, usually less than once a year nationwide.

Civil rights lawyer Ben Crump, who is representing the Wright family, said he was informed about charges while on a panel discussion alongside the mothers of other young black males killed by police.

“The reason why we are getting due process so quickly in the state of Minnesota for the killing of Daunte Wright is because of the blood of their children,” Mr Crump told reporters in New York City.

Mr Wright’s older brother, Dallas Bryant, told NBC News that the family was hoping for a more serious charge to be filed against Potter.

“I’m not too happy about it but I’ll take every win I can get at the moment,” Mr Bryant, 23, said.

He said he expected protests would continue despite the charge.

“My family wants peace. Me and our family are going to try and do it the right way.”

-with agencies