As the lone woman stood in front of a row of riot police in the US, her flowing dress and bare arms in sharp contrast to the officers' armour, she gave off an air of peaceful determination and defiance.

New Orleans-based photographer Jonathan Bachman took the image in Baton Rouge, Louisiana, on Saturday, local time, while covering a protest against recent police shootings of black men in the US.

It was one of scores of demonstrations held across the country following the deaths of Philando Castile and Alton Sterling in separate police shootings in the past week.

Bachman's photo was shared widely on social media, where it was labelled a "powerful" and "legendary" image that would emerge as representative of the Black Lives Matter protests that are spreading across the US.

During Saturday's protest, a group of demonstrators blocked the Airline Highway outside the Baton Rouge Police Department headquarters.

In response, a large number of police officers came out in riot gear and tried to clear the protesters from the road, Bachman told The Atlantic.

The officers "arrested three to four people", Bachman said, and he began capturing images of several protesters confronting the police line.

Over his right shoulder Bachman then heard the woman, who was standing in the first lane of the road, suggesting she was going to be arrested.

"It happened quickly, but I could tell that she wasn't going to move, and it seemed like she was making her stand. To me it seemed like: 'You're going to have to come and get me,' " Bachman told The Atlantic.

"And I just thought it seemed like this was a good place to get in position and make ... an image, just because she was there in her dress and you have two police officers in full riot gear.

"It wasn't very violent. She didn't say anything. She didn't resist, and the police didn't drag her off.

"It's representative of the peaceful demonstrations that have been going on down here. I understand that officers have been hurt in other cities, but down here it's remained peaceful."

The woman, who has not been publicly identified, was arrested on Saturday and remained in jail on Sunday, local time, the New York Daily News reported.

The Atlantic's senior political editor, Yoni Appelbaum, described the image as a "remarkable picture".

"There are images that are impossible to forget, searing themselves into our collective consciousness. One man staring down a column of tanks in Tiananmen Square. A high-school student attacked by police dogs in Birmingham, Alabama. This is such a photo," he wrote. "Once seen, it cannot be unseen."

The woman was arrested at the start of the protest, when Bachman said it was peaceful, but the Baton Rouge Police Department later said 102 people were arrested, most of them later in the night.

"In addition to the arrests, 3 rifles, 3 shotguns and 2 pistols were confiscated. A Baton Rouge Police Officer had several of his teeth knocked out as a projectile was thrown from the protest," the police department said in a statement.

"It appears the protest at Baton Rouge Police Headquarters have become more violent as out of town protesters are arriving. Any protest which becomes violent will be immediately dispersed."