Minnesota state investigators on Friday arrested Derek Chauvin, the police officer accused of murdering unarmed black man George Floyd in the city of Minneapolis earlier in the week.
Just an hour later, Hennepin County Attorney Mike Freeman announced that Chauvin had been charged with third-degree murder and manslaughter.
Freeman told a news conference that it was "by far the fastest we've ever charged a police officer."
The latest developments come after three days of protests in the Upper Midwest US city, which have escalated in violence, with demonstrators overnight setting ablaze a police precinct that had been abandoned by officers.
On Monday, Chauvin was seen in an explosive video pressing his knee to the neck of handcuffed Floyd for at least five minutes. The victim can be seen writhing in pain and pleading: "I can't breathe."
The 46-year-old died the same day.
Chauvin was fired later Monday along with three other officers involved in the incident.
Governor demands end to protests
News of the arrest and charges came shortly after state governor Tim Walz urged an end to the protests, while also promising "swift" justice in the case. Walz also promised there would be reckoning with the racial injustices behind the unrest.
"The fire is still smoldering in our streets. The ashes are symbolic of decades and generations of pain, of anguish unheard,'' Walz said. "Generations of pain is manifesting itself in front of the world – and the world is watching.''
Walz said the state's National Guard would work to restore order after three nights of arson, looting and vandalism. Walz said there had been an "abject failure" in the way the unrest had been dealt with, and that the state would now lead the response.
"We have to restore order to our society before we can start addressing the issue," Walz told a briefing, referring to decades of racial division in the US. "We cannot have the looting and recklessness that went on."
Walz also apologized for the arrest of a CNN reporter and his crew who were taken away in handcuffs while reporting live on television early on Friday.
No explanation was given by the officers as they escorted away reporter Omar Jimenez, a producer and camera operator away. They were released about an hour after being arrested.
The team had been reporting close to a police precinct that was burned overnight. The precinct, which police had abandoned, was set alight after some demonstrators pushed through barriers around the building, smashing windows and chanting slogans.
Some protesters doused their faces with milk after being exposed to tear gas fired by police.
National Guard deployed
The National Guard on Friday said it had been activated by Governor Tim Walz, with nearly 500 soldiers and airmen in position to support rotating missions by morning.
"Our troops are trained to protect life, preserve property and ensure people’s right to peacefully demonstrate," said Maj. Gen. Jon Jensen, from the Minnesota National Guard.
US President Donald Trump on Friday threatened to stop looters in Minneapolis with deadly military force, tweeting that "when the looting starts, the shooting starts."
Twitter took the unprecedented step of hiding the Trump tweet behind a warning banner that accused the president of "glorifying violence."