AP - Thousands of protesters ignored a curfew and vows of a forceful police response to take to the streets of Minneapolis for a fourth night, as the anger stoked by the death of George Floyd in police custody in the city spread across the US.
The Pentagon on Saturday ordered the Army to put military police units on alert to head to the city on short notice at President Donald Trump's request, a rare step which came as the violence spread to other areas including Detroit, Atlanta and New York City.
Criminal charges filed on Friday morning against the white officer who held his knee for nearly nine minutes on the neck of Floyd, a black man, did nothing to stem the anger. Derek Chauvin, 44, is charged with third-degree murder and second-degree manslaughter.
Minneapolis police said shots had been fired at officers during the protests but no-one was injured.
The new round of unrest came despite Minnesota governor Tim Walz vowing earlier on Friday to show a more forceful response. By early Saturday morning, Mr Walz acknowledged he did not have enough manpower.
"We do not have the numbers," he said. "We cannot arrest people when we are trying to hold ground."
Mr Walz said he is moving quickly to mobilise more than 1,000 more National Guard members, for a total of 1,700, and is considering the potential offer of federal military police. But he warned even that might not be enough, saying he expects another difficult night on Saturday.
While not all the protests have been violent, anger fills the streets of Minneapolis.
Local resident Ben Hubert, 26, said he was not surprised people were breaking the curfew and starting fires.
"I'm outraged," he said of the Floyd case. "But I'm also sad. The injustice has been going on for so long. It's been swelling for years."
Chauvin is also accused of ignoring another officer who expressed concerns about Floyd as he lay handcuffed on the ground, pleading that he could not breathe while Chauvin pressed his knee into his neck for several minutes. Floyd, who was black, had been arrested on suspicion of using a counterfeit note at a store.
Chauvin, who was fired along with three other officers who were at the scene, faces more than 12 years in prison if convicted of murder.
A lawyer for Floyd's family welcomed the arrest but said he expected a more serious murder charge and wants the other officers arrested too.
Prosecutor Mike Freeman said more charges were possible, but authorities "felt it appropriate to focus on the most dangerous perpetrator".
Protests nationwide have been fuelled by outrage over Floyd's death and years of police violence against African Americans.
In Atlanta, protesters smashed windows at CNN headquarters, set a police car on fire and struck officers with bottles.
The state's governor declared a state of emergency to activate the state National Guard to help deal with the protests.
The Guard was also on standby in the District of Columbia, where a crowd grew outside the White House and chanted against Mr Trump. Some protesters tried to push through barriers set up by the Secret Service along Pennsylvania Avenue, and threw bottles and other objects at officers wearing riot gear, who responded with pepper spray.
Other large demonstrations in New York, Los Angeles, Houston and dozens of other cities ranged from people peacefully blocking roads to repeated clashes with police.
A post-mortem examination said the combined effects of being restrained, potential intoxicants in Floyd's system and his underlying health issues, including heart disease, likely contributed to his death.
Mr Trump said on Friday that he had spoken to Floyd's family and "expressed my sorrow".
He called video of the arrest "just a horrible thing to witness and to watch, it certainly looked like there was no excuse for it".