Police and protesters have clashed for a second night in the US city of Minneapolis after an unarmed black man died in police custody.
Tear gas was fired by police, while protesters threw rocks and sprayed graffiti. Businesses were also looted.
George Floyd, 46, died on Monday and video showed him gasping for breath as a white policeman knelt on his neck.
Four police officers have been fired, with the mayor saying that being black “should not be a death sentence”.
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The renewed clashes on Wednesday came just hours after the city’s mayor called for criminal charges to be brought against the policeman who was filmed holding Mr Floyd.
There was also looting and vandalism, with some buildings close to the demonstrations being destroyed by fire.
The incident echoes the case of Eric Garner, who was placed in a police chokehold in New York in 2014. His death became a rallying call against police brutality and was a driving force in the Black Lives Matter movement.
A number of celebrities and athletes, including John Boyega, LeBron James, Beyonce, and Justin Bieber, have also weighed in, expressing outrage over the incident and condemning racism.
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How have the protests unfolded?
They began in the afternoon on Tuesday, when hundreds of people came to the intersection where the incident had taken place.
Organisers tried to keep the protest peaceful and maintain coronavirus social distancing, with demonstrators chanting “I can’t breathe” and “It could’ve been me”.
A crowd of hundreds then marched to the 3rd Precinct, where the officers involved in the death are thought to have worked.
One protester told CBS: “It’s real ugly. The police have to understand that this is the climate they have created.”
On a second night of demonstrations on Wednesday, protesters pelted rocks and some threw tear-gas canisters back at the officers.
The crowd grew into the thousands as the evening went on, and there was a standoff outside the police station where officers formed a human barricade to prevent protesters gaining entry.
A nearby supermarket was vandalised, and people were seen fleeing the store with baskets of looted goods. Other businesses were seen in flames and some appeared to have been entirely destroyed.
“Tonight was a different night of protesting than it was just the night before,” a police spokesman told the New York Times.
Minneapolis mayor Jacob Frey has requested the state national guard’s assistance in the wake of the protests, KARE11 News reported.
He earlier said: “We can have peaceful demonstrations, but I also have to ensure the safety of everyone in the city.”
The incident has also sparked solidarity protests in Chicago, Illinois, Los Angeles, California, and Memphis, Tennessee.
What happened to George Floyd?
Officers responding to reports of the use of counterfeit money had approached Mr Floyd in his vehicle on Monday.
According to police he was told to step away from the vehicle and physically resisted officers.
A police statement said: “Officers were able to get the suspect into handcuffs and noted he appeared to be suffering medical distress.”
Video taken at the scene does not show how the confrontation started. It shows a white officer using his knee to pin Mr Floyd to the ground by the neck.
Mr Floyd groans “please, I can’t breathe” and “don’t kill me” as bystanders urge officers to let him go.
He ceases to move and an ambulance arrives to take him to hospital where he was pronounced dead.
What was the official response?
Minneapolis Mayor Jacob Frey said it was the “right call” to fire the officers.
He said: “Being black in America should not be a death sentence. For five minutes we watched as a white police officer pressed his knee into the neck of a black man. For five minutes. When you hear someone calling for help, you are supposed to help.”
President Donald Trump on Wednesday said that the FBI and Justice Department are investigating Mr Floyd’s death at his request.
The US Attorney’s Office in Minnesota, the FBI and the civil rights division of the justice department said on Thursday that the “robust criminal investigation” into the circumstances of Mr Floyd’s death is a “top priority”.
The inquiry will determine whether the actions of the police officers violated federal law by depriving Mr Floyd of his constitutional rights.
The Minnesota police handbook states that officers trained on how to compress the neck without applying direct pressure to the airway can use a knee under its use-of-force policy. This is regarded as a non-deadly-force option.
Why is the case so sensitive?
Allegations of police brutality have been constantly highlighted since the start of the Black Lives Matter movement. It began after the acquittal of neighbourhood watchman George Zimmerman in the shooting death of African-American Trayvon Martin in February 2012.
The deaths of Michael Brown in Ferguson and Eric Garner in New York in 2014 sparked huge protests.
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“I can’t breathe” became a national rallying cry as Garner, an unarmed black man, uttered the phrase 11 times after being detained by police in a chokehold on suspicion of illegally selling loose cigarettes.
The New York City police officer involved in Garner’s arrest was fired five years later, but no officer was charged.
Recent allegations of police wrongdoing include the shooting of a black woman in her home in Louisville by three white Kentucky policemen and the shooting of a man by an officer in Maryland.