Curfews have been ordered in cities across the US in an attempt to stem the violent clashes between protesters and police over the death of George Floyd.
Widespread demonstrations have taken place, with riot police using tear gas and rubber bullets after their vehicles were set alight in several cities.
President Donald Trump blamed looters and anarchists for the violence.
Floyd, a 46-year-old African American, was killed while in police custody in Minneapolis on Monday (local time).
Former policeman Derek Chauvin, 44 and white, has been charged with his murder and is due to appear in court on Monday.
In footage that went viral online, Chauvin can be seen kneeling on Floyd's neck for several minutes. Floyd repeatedly says that he is unable to breathe.
Three other officers present at the time have also since been sacked.
What's the latest on the protests?
Large demonstrations have taken place in at least 30 cities across the US.
In Chicago, protesters threw stones at riot officers, who responded by launching tear gas canisters. Several people were arrested on Saturday.
One of the cities worst affected by unrest is Los Angeles. California Governor Gavin Newsom declared a state of emergency in the city and activated the National Guard - the reserve military force that can be called on by the US president or state governors to intervene in domestic emergencies.
The entire city is under a curfew. Numerous shops have been looted, including on the famous retail avenues, Melrose and Fairfax, while overhead footage showed fires burning. Earlier police fired rubber bullets and hit protesters with batons.
Mayor Eric Garcetti said this was "the heaviest moment I've experienced" since the riots in 1992 that were sparked by the acquittal of police over the beating of Rodney King.
In New York, video showed a police car driving into a crowd of protesters. Mayor Bill de Blasio said the situation was not started by the officers, but Congress Representative Alexandria Ocasio-Cortez said his comments were unacceptable and he should not be making excuses for the officers.
For the second day running, a large crowd converged on the White House in Washington, DC.
In Atlanta, Georgia, where buildings were vandalised on Friday, a state of emergency was declared for some areas to protect people and property.
Thousands of people also marched through the streets of Minneapolis, New York, Miami, Atlanta and Philadelphia.
Overnight curfews have been now been declared in Minneapolis, Atlanta, Los Angeles, Philadelphia, Portland and Louisville - among other cities.
However, protesters in several cities continue to defy the curfews and widespread looting has been taking place.
In Minnesota, hundreds of troops from the National Guard - a reserve military force that can be called on by the US president or state governors to intervene in domestic emergencies - were brought in late on Friday.
Attacks on media
Two members of a Reuters TV crew were hit by rubber bullets and injured in Minneapolis when police moved into an area occupied by about 500 protesters shortly after the 8pm curfew.
Footage taken by cameraman Julio-Cesar Chavez showed a police officer aiming directly at him as police fired rubber bullets and tear gas to disperse the crowd.
Minutes later, Chavez and Reuters security advisor Rodney Seward were struck by rubber bullets as they took cover at a nearby gas station.
On footage captured as they ran for safety, several shots are heard ringing out and Seward yells, "I've been hit in the face by a rubber bullet."
Asked about the incident, Minneapolis Police Department spokesman John Elder requested a copy of the video and made no immediate comment.
Seward is seen in later footage being treated by a medic near the scene for a deep gash under his left eye. Both men sustained injuries to their arms, and Chavez was hit in the back of the neck.
The incident was the latest attack on a journalist covering the protests. A black CNN journalist was arrested on camera while covering the protests in Minneapolis yesterday.
A Louisville, Kentucky, television reporter yelled, "I'm getting shot" as she was seen live on camera being hit by what appeared to be a pepper ball. The Louisville Metro Police Department apologised for that incident.
What has Trump said?
On Saturday evening, Trump said that Floyd's death had "filled Americans with horror, anger and grief".
"I stand before you as a friend and ally to every American seeking peace," he said in a televised address from Cape Canaveral in Florida, following the launch into orbit of two Nasa astronauts by billionaire Elon Musk's SpaceX company.
The president denounced the actions of "looters and anarchists", accusing them of dishonouring the memory of Floyd. What was needed, he said, was "healing not hatred, justice not chaos".
"I will not allow angry mobs to dominate - won't happen," he added.
Trump has blamed the mayor of Minneapolis - a Democrat - for failing to control the protests, which are the worst since he took office.
He said that if the violence was not brought under control, the deployment of the National Guard would do the job.
The president's Democratic Party rival, Joe Biden, has accused him of giving oxygen to bigotry and said those responsible for Floyd's death must be held accountable.
- BBC / Reuters