Protests against the shootings of two black men by police officers shut down main arteries in a number of US cities on Saturday (local time), leading to numerous arrests, but remained mostly peaceful, except for scuffles with riot police in Baton Rouge.
Undeterred by heightened concerns about safety at protests after Micah Johnson killed five police officers in Dallas on Thursday night, organisers went ahead with marches in the biggest metropolis, New York City, and Washington D.C, the nation's capital, among other cities.
It was the third straight day of widespread protests after the fatal shooting of Alton Sterling, 37, by police in Baton Rouge on Tuesday and the death of Philando Castile, 32, on Wednesday night in a St. Paul, Minnesota suburb.
The most recent shooting deaths by police come after several years of contentious killings by law enforcement officers, including that of Michael Brown, a teenager whose death in the summer of 2014 caused riots and weeks of protests in the St Louis suburb of Ferguson.
Early on Saturday evening, hundreds of protesters shut down I-94, a major thoroughfare linking the Twin Cities, snarling traffic for about two hours.
Despite warnings to disperse, St Paul police said protesters threw objects, injuring one officer. The police then began making arrests and used smoke bombs to scatter the crowd.
A march in Baton Rouge saw scuffles between riot police and Black Panther activists, several of whom carried shotguns, as Louisiana law allows for weapons to be carried openly. A police spokesman said several arrests were made and two weapons recovered during the confrontation.
After a short standoff later in the evening, riot police made multiple arrests.
Protests also took place Saturday in Nashville, where protesters briefly blocked a road, and in Indianapolis.
A rally in San Francisco also briefly blocked a freeway ramp, according to local media.
Hundreds of protesters marched from City Hall to Union Square in New York. The crowd swelled to around a thousand people, closing down Fifth Avenue.
Some in the crowd chanted "No racist police, no justice, no peace" as rain fell in New York.
"I'm feeling very haunted, very sad," said Lorena Ambrosio, 27, a Peruvian American and freelance artist, "and just angry that black bodies just keep piling and piling up."
New York police said separately they arrested about a dozen protesters for shutting down a major city highway.
Dallas police respond to threat
Dallas police have given the all clear, hours after security levels were raised at their headquarters in the city following an anonymous threat.
They said they had received an anonymous threat.
A nearby parking lot was searched for a "suspicious person" but no-one was found. SWAT officers were earlier deployed at the main building.
Dallas police said its officers - using dogs - searched the parking lot but the hunt turned up nothing.
In a statement earlier on Saturday, police said: "The Dallas Police Department received an anonymous threat against law enforcement across the city and has taken precautionary measures to heighten security."
Johnson, who was himself killed after the attacks in Dallas, supported black militant groups who encouraged violence against police.
Dallas police chief David Brown said Johnson had told a negotiator that he had wanted to kill white people, especially white police officers, because he was angry about the recent shootings of black men by police.
Police later found bomb-making materials, rifles, ammunition and a combat journal at Johnson's home.
President stresses unity
US President Barack Obama says the US is "not as divided as some have suggested" in the wake of fatal shootings involving African-Americans.
Mr Obama said "it was just not true" the US was returning "to the situation in the 60s".
His comments, on the side of a Nato summit in Warsaw, echoed those made earlier by vice-president Joe Biden, who said Americans had a duty to stand up against injustice, but that people also needed to support police.
Mr Obama said Americans of "all races, all backgrounds", including many of those who were protesting, were outraged by the Dallas killings.
The unity shown in the wake of the attack was a strong foundation on which to build, he said.
"When you start suggesting that, somehow, there is this enormous polarisation and we are back to the situation in the 60s, it's just not true," he said.
"You are not seeing riots and you are not seeing police going after people who are protesting peacefully.
"We have seen almost uniformly peaceful protests and we have seen, uniformly, police handling those protests with professionalism.
"And so, as tough, as hard, as depressing as the loss of life this week, we have got a foundation to build on. We just have to have confidence that we can build on those better angels of our nature."
- BBC / Reuters