The Minneapolis police officer accused of killing an unarmed African American man has been charged with murder as authorities sought to restore peace after three nights of violent protests left parts of the city in flames.
Derek Chauvin is one of four officers fired after an explosive video emerged showing him kneeling on the neck of a handcuffed George Floyd for at least five minutes on Monday.
"This case is now ready, and we have charged it," said county prosecutor Mike Freeman amid outrage over the latest death of an African American at the hands of the police.
Mr Freeman said the three other officers were under investigation, and that he anticipated charges.
Protesters cheer as the Third Police Precinct burns behind them on May 28, 2020 in Minneapolis, Minnesota. Source: Getty Images North America
The announcement came hours after hundreds of troops were deployed to the streets of Minneapolis and St. Paul to stem what would be a fourth night of violent protests.
Scores of buildings have been burned and looted across the so-called Twin Cities, including a police station associated with the four officers.
As President Donald Trump labelled the protesters "thugs" and threatened a harsh crackdown, Minnesota Governor Tim Walz warned that he was considering a curfew.
"This is volatile. This has been building for decades," he said of tensions between police and African Americans.
A protester walks out of the Minneapolis 3rd Precinct police building as it burns on May 28, 2020 Source: Getty Images North America
"The first task at hand is, get civil control back, and get justice moving quickly and fairly."
Barack Obama, the country's first black president, said Friday he shared the "anguish" of millions of Americans over 46-year-old Floyd's death.
"This shouldn't be 'normal' in 2020 America," Mr Obama said in a statement.
Mr Obama's former vice president Joe Biden, who is running for president, called for justice for Mr Floyd and said it was time to heal the "open wound" of systemic racism in the United States.
George Floyd died while in police custody in Minneapolis. Source: AAP
But Mr Trump lashed out at local officials for letting protests get out of hand and threatened a violent federal crackdown.
'People are angry'
"These THUGS are dishonouring the memory of George Floyd, and I won't let that happen," Mr Trump tweeted.
"Just spoke to Governor Tim Walz and told him that the Military is with him all the way. Any difficulty and we will assume control but, when the looting starts, the shooting starts."
The post sparked an angry push-back from critics who interpreted it as an incitement to violence, although Mr Trump later denied this was his intention.
Officials in the Twin Cities and across the US were bracing for more violence Friday after protests broke out in New York, Louisville, Memphis, Denver and Phoenix.
A supporter holds a photo of George Floyd on the site where the 46-year-old died in police custody. Source: Star Tribune
Several hundred people angrily protested outside the White House in tense scenes that have spread to several cities across the country.
Protests had also spread to New York, Houston, Detroit, Las Vegas, San Jose and Memphis.
Demonstrators gathered outside the CNN building in Atlanta, climbing on the large logo outside and plastering it with paint.
President Donald Trump was in the mansion during the Washington protest that converged on a park across the street from the White House, where several dozen Secret Service agents lined barricades.
"People are angry they are frustrated because this is not the first police killing they have seen around the country," civil rights activist Al Sharpton told MSNBC.
"The tape is more than enough to establish probable cause... to make an arrest. There is no reason these four policeman have not been arrested by now."
Mr Freeman said that, even with the video as evidence, his department was required to build an airtight case before making arrests
"We have a difficult burden of proof. We entrust our police officers to use a certain amount of force," he told reporters.
Excessive force had to be established "beyond a reasonable doubt," he added.
Mr Chauvin and his three colleagues are under investigation by the FBI and the Department of Justice for federal crimes, specifically civil rights violations that, because a death was involved, could bring life in prison.
"The Department of Justice has made the investigation in this case a top priority," Erica MacDonald, the US federal attorney for Minnesota, said Thursday.
