Two white police officers will not be charged over the death of a black man whose shooting was filmed and fuelled protests throughout the United States.

Alton Sterling was shot and killed by police in Baton Rouge outside a convenience store where he was selling home-made CDs.

Two phone videos of Mr Sterling's deadly struggle with the two officers, Blane Salamoni and Howie Lake, quickly spread on social media after the shooting.

The videos show the 37-year-old struggling with the police officers after they had been called to a complaint that Mr Sterling had threatened the caller with a gun outside the shop.

A police report said Mr Sterling was initially jolted with a stun gun after he did not obey the officers' commands to put his hands on the bonnet of a car.

The report also said the officers saw the butt of a gun in one of Mr Sterling's trouser pockets and saw him try to reach for it before he was shot.

The police officers had Mr Sterling pinned on his back on the floor when gunfire erupted, moments after someone can be heard shouting: "He's got a gun!"

Baton Rouge's police chief has said Mr Sterling was armed and the store's owner has said he was not holding a gun during the shooting, but he saw officers remove one from his pocket afterwards.

As a convicted offender, Mr Sterling could not legally carry a gun.

Court records show he pleaded guilty in 2011 to being a felon in possession of a firearm and illegally carrying a weapon and was arrested in May 2009 after an officer confronted him outside another store where he was selling CDs.

Mr Sterling's death sparked widespread protests during which police arrested almost 200 people, leading to lawsuits accusing police of using excessive force and violating civil rights.

The killing of Alton Sterling sparked nationwide protests. Credit: PA

Although the US Justice Department will not charge Mr Salamoni and Mr Lake, state authorities can conduct their own investigation and pursue criminal charges.

No public announcement was made by the department and many officials in Baton Rouge said they had not been notified, including John Bel Edwards, the Louisiana Governor.

"The Governor's Office has not been notified of a timeline or decision regarding the Alton Sterling investigation," a spokesperson for Mr Edwards.

They continued: "We have been in constant contact with the US Attorney's Office and were assured that both our office and the Sterling family would be given advance notice."

Dozens of people gathered at the scene of the shooting on Tuesday after hearing of the news and held a vigil.

One of Mr Sterling's aunts led the crowd in chants of "No justice, no peace!"

"It's been almost a year and we're still suffering like it happened yesterday," said Veda Sterling.

"We need closure. We need a conviction. We need justice."

Local activist Arthur Reed said he broke the news to another of Mr Sterling's aunts, Sandra, in a phone call.

He said she broke down and was "heartbroken", not only because of the decision but because the Justice Department did not notify the family first.

"We just think it wasn't done properly," he said.

Tuesday's decision is the highest-profile move not to bring charges against police officers in a deadly shooting since Jeff Sessions became US Attorney General.

Mr Sessions has said that the Justice Department is committed to holding individual officers accountable when they break the law, but also believes too much federal scrutiny of police forces can diminish officers' effectiveness and hurt morale.

Police said they had dashcam and bodycam video and shop footage of the shooting, but none has been released and a coroner's report on Mr Sterling's post-mortem examination has been sealed.

Both Mr Salamoni and Mr Lake were placed on administrative leave, a standard procedure, following the shooting.

The two officers both had had two previous "use of force" complaints each, but records indicate they were cleared in all cases.