Image caption Keith Lamont Scott (L) and Officer Brently Vinson

North Carolina prosecutors have said a Charlotte police officer acted lawfully when he shot and killed a fellow black man, Keith Lamont Scott, in September, and will not face charges.

The shooting triggered several nights of protests across the city.

Scott's family say he was unarmed but police insist he had a gun.

Prosecutors revealed surveillance footage appearing to show a holstered gun on his ankle.

Footage released directly after the shooting by police and by Scott's wife had been inconclusive.

District Attorney Andrew Murray, who made the announcement, said 15 experienced prosecutors had unanimously recommended there was insufficient evidence to charge Officer Brentley Vinson.

Mr Murray said he had informed the family of the verdict prior to his public announcement.

Image copyright AP Image caption Mr Murray said additional video footage proved Scott had been armed

After the news was released, police were put on high alert and the city of Charlotte released a statement: "We recognize that for some members of our community, this news will be met with different reactions.

"No matter where you stand on the issue, the events surrounding the Scott shooting have forever changed our community, and we intend to learn from and build a stronger Charlotte because of it."

North Carolina's governor declared a state of emergency in the city in September after protesters turned violent.

Lawyers for Scott's family said they might still consider filing a lawsuit because of different standards for criminal charges and civil liability.

Mr Vinson was placed on administrative leave following the shooting - common practice after such incidents.

The "Black Lives Matter" movement, which led many of the protests following Scott's death, was started after the deaths of unarmed black men at the hands of police.

According to one research group, over 100 unarmed black people were killed by the police in 2015 and a string of riots occurred following similar shootings this year.

'Pistol cocked'

Details of the shooting released by Mr Murray at a news conference state that plainclothes police went to an apartment complex on 20 September to look for a suspect - not Scott - with an outstanding warrant.

Prosecutors say Scott parked in the apartment complex's car park, beside officers, after going into a local shop.

Footage from the shop reveals that Scott was carrying a weapon, the prosecutors say.

Image copyright Reuters Image caption Scott looks at police after getting out of his car on 20 September

Scott then allegedly proceeded to smoke a marijuana cigarette and hold up a semi-automatic hand gun while in his car.

He then exited the car and officers approached. At that point police deemed him a threat and Officer Vinson fired his weapon.

Image copyright Reuters Image caption Police say they found Scott's DNA on the handgun recovered from the scene

Scott was pronounced dead later at a local hospital from gunshot wounds to his back and abdomen.

Prosecutors say that Scott's DNA was found on a handgun at the scene.

They say the gun was cocked, the safety catch was off and there were bullets in the chamber. Investigators also found a receipt for the purchase of ammunition in Scott's wallet.