PROTESTERS angry over the fatal shooting of a black man by two white Louisiana police officers held a rally at the convenience store where he was shot.

Other demonstrators gathered in front of the Baton Rouge police department and at the state Capitol, demanding justice for Alton Sterling, 37, who was shot dead on Tuesday.

The Department of Justice has opened an investigation into his death, which has angered many in the black community.

The latest protests came after overnight demonstrations had resulted in 30 arrests. The rally outside the police building was at times tense again, as protesters faced off against police dressed in riot gear.

Several hundred people shouted "No justice! No peace!" and waved home-made signs as passing cars honked their support.

Some drivers stopped to offer bottles of water.

At one point police in riot gear came out to clear the road, as demonstrators yelled at them.

A police spokesman said two firearms were confiscated and several arrests made.

Baton Rouge resident Marie Flowers came to the protest with her three children. She said people in the north Baton Rouge neighbourhood where the shooting happened are frustrated.

She gestured to her 12-year-old son and said they were there to protect people like him.

"Black boys are being killed and this is just the culmination of what has been going on for decades," she said.

Lael Montgomery of Baton Rouge was at the convenience store where Mr Sterling was shot.

"I've been in active in the community for years. We have been suffering police brutality for a long time. A lot of racism has been going on here for a long time," he said. "I have kids. They need to be raised in a better environment than they're in."

Members of the New Black Panther Party for Self Defence called for the arrest of the officers involved in Mr Sterling's shooting.

"These are human rights violations," Krystal Muhammad shouted to the crowd at the convenience store before heading over to the police department.

"They are not operating as human beings. They are being predators on our communities across America."

Baton Rouge police said they are investigating a newspaper website's video that appears to show an officer with his weapon temporarily drawn at one point early on Saturday morning as angry protesters confronted police.

"We are reviewing the video. It's difficult to tell why the officer pulled his weapon. We are working to identify this officer so we can better understand the reason he might have done this," the police said.

"After the Dallas murder of five officers at a protest the night before officers are very cautious and on the lookout for any threat.

Tensions were very high last night on both sides. But in the end cooler heads prevailed."


Vonny Moyes: Why white people need to stop snapping back that 'all lives matter'