Hundreds of people marched through the streets of Baton Rouge on Thursday (7 July) after Louisiana police shot dead a black man outside one of the city's convenience stores. Alton Sterling, 37, died on Tuesday from multiple gunshot wounds to the chest and back after being apprehended by police in the state's capital Baton Rouge.

The shooting comes amid heightened tensions about the killing of black men at the hands of police in the US. There were more than 1,000 fatal shootings by police in the US last year, with black men killed in disproportionate numbers.

Less than 48 hours after Sterling's death, another black man, Philando Castile, was fatally shot by police in Minnesota. Castile's girlfriend live-streamed the aftermath of the shooting, which happened shortly after officers pulled over the pair in Minneapolis for a broken tail light.

Some protesters in Baton Rouge called for the two officers involved in the shooting of Sterling to be prosecuted.

"There is not going to be a riot until they show they are not going to prosecute these people," said Arsby, a 53-year-old truck driver who declined to give his last name, as he joined other peaceful protesters in circling the Baton Rouge store where Sterling died. "Right now it's just started."

Those marching were seen holding signs saying "stop killing us" and "all lives matter", as a brass band played music. Police watched on from the side.

The US Justice Department said on Wednesday it would investigate the killing, while US presidential hopeful Hillary Clinton described the shooting as a "tragedy".

"From Staten Island to Baltimore, Ferguson to Baton Rouge, too many African American families mourn the loss of a loved one from a police-involved incident," Clinton said. "Something is profoundly wrong when so many Americans have reason to believe that our country doesn't consider them as precious as others because of the colour of their skin."

Protester Tammara Crawford, a 33-year-old mother and school administrator in Baton Rouge, said: "Now, all eyes are in Baton Rouge. What may have been easier to cover up before because it was just us ... now they've woken up the sleeping lions."

Shooting captured on video

Officers involved in the shooting said they had been called at about 12.35am to reports of a man selling CDs and wearing a red shirt threatening another man with a gun outside the Triple S Food Mart in North Foster Drive.

Graphic video footage taken by a nearby member of the public shows two attending officers become involved in a stand-off with Sterling. He is told to "get on the ground" before being tackled to the floor where officers attempt to restrain him.

Alton Sterling: New mobile phone footage emerges of deadly police shootingStoryful

But as the struggle continues, shouts of "he's got a gun" are heard and one officer pulls out his firearm. He then shouts: "You f*****g move, I swear to God," at Sterling, before the sound of five gunshots is heard.

The shocked individual taking the mobile phone footage of the incident asks: "They shot him?" A woman heard crying in the background replies: "Yes."

Baton Rouge Police Department (BRPD) said Sterling died at the scene and that both officers involved in the shooting have been placed on administrative leave, as is standard department policy.

Adults can 'openly carry' guns in public in Louisiana

Investigators are still trying to piece together the moments leading up to the shooting using CCTV footage and police video. Abdullah Muflahi, owner of Triple S store who witnessed the shooting, said Sterling was armed but that he didn't take out the firearm during the incident. He said the police "didn't have to shoot him" and that they "could have handled it differently".

He told reporters: "I walked out, they were trying to get him on top of a car that was parked out here. They kind of slammed [him] at first. He was resisting. They pulled back [and] tasered him. Another cop tackled him. Both cops got on top of him, one screamed 'gun' and that's when the other guy shot him."

He went on to claim that the police officers involved later reached into Sterling's pocket and pulled a firearm out. The state of Louisiana allows residents to "open carry" handguns in public but only if they are an adult and have no criminal convictions. Carrying a concealed weapon requires a permit.