Protesters clashed with police in US cities over the death of an unarmed African American at the hands of police in Minneapolis.
Hundreds of people gathered outside the White House, which was briefly detained on Friday, demanding justice for the death of George Floyd.
Demonstrations were held in Minnesota, New York and California.
A former Minneapolis police officer was arrested and charged with murder for the death of Floyd in custody.
Derek Chauvin, who is white, was shown in footage kneeling on his 46-year-old neck on Monday. He and three other officers have since been fired.
Chauvin, 44, is due to appear in court in Minneapolis for the first time on Monday.
President Donald Trump described the incident as "a terrible, terrible thing" and said that he had talked to Floyd's family, whom he described as "wonderful people".
What happened during the protests?
On Friday night, crowds gathered near the White House in Washington, DC, waving photographs of Mr. Floyd and singing "I can't breathe" – invoking his last words and those of Eric Garner, a black man who died after being held in a police strangulation in New York in 2014.
The White House was then temporarily blocked, with the US Secret Service closing entrances and exits.
The curfew was requested for the twin cities of Minneapolis-Saint Paul from 8:00 pm to 6:00 am, both on Friday and Saturday night. But other demonstrator meetings were reported after the curfew, and buildings and vehicles were set on fire later.
There have been violent clashes between protesters and police in several cities, including New York, Los Angeles, Chicago, Denver, Houston, Louisville, Phoenix, Columbus and Memphis.
In Atlanta, buildings were vandalized and a police vehicle was set on fire when protesters gathered near the offices of CNN.
In Dallas, officers threw tear gas canisters after they were hit by rocks.
Although Chauvin was charged with third-degree murder and second-degree murder for his role in Floyd's death, protesters want the other officers involved to face justice.
The case rekindled America's ire for police killings by black Americans, and protests across the country follow days of looting and arson in Minneapolis.
On Thursday, during the third night of protests, a police station was set on fire. Several buildings have been burned, looted and vandalized in recent days, leading to the activation of troops from the state National Guard.
What did the prosecutor say?
Hennepin County Attorney Mike Freeman said he "anticipates charges" for the other three officers, but did not provide further details.
Freeman said his office "took the case as quickly as the evidence was presented to us."
"This is by far the fastest we have ever accused a police officer," he noted.
According to the criminal complaint, Chauvin acted with "a depraved mind, without considering human life".
How George Floyd died?
The county coroner's full report was not released, but the complaint said the post-mortem examination found no evidence of "traumatic asphyxiation or strangulation".
The coroner noted that Floyd had underlying heart problems and the combination of these, "potential intoxicants in his system" and being restrained by the police "probably contributed to his death".
The report says Chauvin was on his knees on Floyd's neck for eight minutes and 46 seconds – almost three minutes after Floyd was left unanswered.
Almost two minutes before he removed his knee, the other officers checked Mr. Floyd's right wrist and were unable to find one. He was taken to the Hennepin County Medical Center in an ambulance and pronounced dead about an hour later.
The Minnesota police manual states that officers trained in how to compress a detainee's neck without applying direct pressure to the airways can use a knee under their policy of using force. This is considered a non-deadly force option.
What did the president say?
At the White House on Friday, Trump said he asked the justice department to speed up an investigation announced on Friday about whether any civil rights law was violated in Floyd's death.
The president also said that "looters should not drown out the voice of so many peaceful protesters".
Rather, he described the protesters as "thugs" who dishonored Floyd's memory.
The social media network Twitter accused Trump of glorifying violence in a post that said, "When the looting begins, the shooting begins."
What is the reaction?
Floyd's family and his lawyer, Benjamin Crump, said the arrest was "welcome, but delayed".
The family said they wanted a more serious and first-degree murder charge, as well as the arrest of the other officers involved.
The statement called for the city to change its policing, saying, "Today, George Floyd's family is having to explain to their children why their father was executed by police on video."
Former US President Barack Obama also commented, "This shouldn't be" normal "in America 2020".
His statement added: "If we want our children to grow up in a nation that lives up to their highest ideals, we can and must be better."
Minnesota Governor Tim Walz said the arrest was "a good first step towards justice".
What happened in prison?
The officers suspected that Floyd had used a counterfeit $ 20 bill and was trying to put him in a police vehicle when he fell to the ground, saying he was claustrophobic.
According to the police, he physically resisted the police and was handcuffed.
The video of the incident does not show how the confrontation started, but a white policeman can be seen with his knee on Floyd's neck, pinning him to the ground.
Floyd can be heard saying "please, I can't breathe" and "don't kill me".
A former local nightclub owner said Chauvin and Floyd worked as security guards at their location in southern Minneapolis until last year, although it is not clear whether they knew each other.