Update 12.20pm The man shot dead by police in Minnesota has been named.
Philando Castile was shot after being stopped for a broken tail light in a suburb of St Paul in Minnesota.
It follows an outcry over the fatal shooting of African American Alton Sterling in Louisiana - as he was pinned to the ground by two white officers.
Earlier A black man has died after being shot by police in the US state of Minnesota.
St Anthony Police Department said the man was taken to hospital after being shot in the suburbs of the state capital, St Paul, but died later.
Interim police chief Jon Mangseth told reporters earlier that the incident began when an officer initiated a traffic stop.
Reports said the man was shot while inside a car with a woman and a child, who were not hurt.
A video posted on Facebook appeared to show a woman sitting in a car with a man whose shirt looked to be soaked in blood, saying an officer had shot her boyfriend.
Both the woman and her boyfriend were black. A white police officer can be seen at the car window, pointing a gun into the car. He can be heard saying: "I told him not to reach for it". The woman answers: "You told him to get his ID, sir."
In the video, the woman says the officer asked her boyfriend for his license and registration. She says the man told the officer it was in his wallet, but that he also had a pistol he was licensed to carry.
"The officer said, 'Don't move,'" the woman in the video says. "As he was putting his hands back up, the officer shot him in the arm four or five times."
The Associated Press could not immediately verify the authenticity of the video.
Dozens of protesters gathered at the scene chanting: "We will stand our ground. We will not move," as officers attempted to clear the area.
The shooting came as the Justice Department launched a civil rights investigation into the video-recorded killing of a black man who was shot as he scuffled with two white police officers in Baton Rouge, Louisiana, which has sparked more protests.