Peaceful rallies have given way to a third night of arson, looting and vandalism in Minneapolis as protesters vented their rage over the death of a black man seen on video gasping for breath while a white police officer knelt on his neck.

The latest spasm of unrest in the state of Minnesota’s largest city went largely unchecked, despite Governor Tim Walz ordering the National Guard activated to help restore order following the first two days of disturbances sparked by Monday night’s fatal arrest of George Floyd, 46.

In contrast with Wednesday night, when rock-throwing demonstrators clashed repeatedly with police in riot gear, law enforcement kept a low profile around the epicentre of the unrest, outside the city’s Third Precinct police station.

Protesters massing outside the building briefly retreated under volleys of police tear gas and rubber bullets fired at them from the roof, only to reassemble and eventually attack the building head on, setting fire to the structure as police seemed to withdraw. Protesters were later seen on the roof.

A car and at least two other buildings in the vicinity were also set ablaze, and looters returned for a second night to a nearby Target discount store, left boarded up and vacant from the previous night, to make off with whatever remained inside.

Fire officials said 16 buildings were torched on Wednesday night.

Protesters in front of the burning Third Police Precinct in Minneapolis, in a third day of demonstrations over the police killing of George Floyd.

Protesters in front of the burning Third Police Precinct in Minneapolis, on the third day of demonstrations over the police killing of George Floyd. Photo: AFP

There was no immediate sign of National Guard troops at the police station, or at a peaceful daytime rally and march around the Hennepin County Government Centre, in downtown Minneapolis.

President Donald Trump on Twitter said that he will send the National Guard troops and “get the job done right” if Mayor Jacob Frey failed to bring the city under control.

“Any difficulty and we will assume control but, when the looting starts, the shooting starts,” he wrote in tweets posted late midnight, US time.

Local, state and federal law enforcement officials sought earlier in the day to ease racial tensions sparked by Floyd’s death by vowing to achieve justice.

Four city police officers involved in the incident, including the one shown pressing his knee into Floyd’s neck as he lay on the ground, moaning, “please, I can’t breathe,” were fired from their jobs the next day.

Flames rise from a liquor store and shops near a police station set on fire during a third night of protests in Minneapolis.

Flames rise from a liquor store and shops in flames, during a third night of protests, looting and vandalism in Minneapolis. Photo: AFP

The Floyd case was reminiscent of the 2014 killing of Eric Garner, an unarmed black man in New York City who died after being put in a banned police chokehold as he, too, was heard to mutter, “I can’t breathe.”

Garner’s dying words became a rallying cry for the Black Lives Matter movement that formed amid a wave of killings of African-Americans by police.

Throughout the day, protesters pressed their demands that the four policemen be arrested and prosecuted.

“There is probable cause right now” to make those arrests, civil rights activist the Reverend Al Sharpton said as he addressed the crowd. “We’re not asking for a favour. We’re asking for what is right.”

Garner’s mother, Gwen Carr, said Floyd’s case was like “opening up an old wound, and pouring salt into it.”

‘Give us time to do this right’

At a morning news briefing, Police Chief Medaria Arradondo publicly apologized to Floyd’s family, conceding his department had contributed to a “deficit of hope” in Minneapolis.

Hours later, officials overseeing investigations from the US Justice Department, FBI, Minnesota Bureau of Criminal Apprehension and prosecutors appealed for calm at a joint news conference, as they gathered evidence.

“Give us the time to do this right, and we will bring you justice,” County Attorney Mike Freeman told reporters. He acknowledged the policeman’s conduct depicted in the video was “horrible,” but said, “My job is to prove that he has violated a criminal statute.”

This still image taken from a May 25, 2020, video courtesy of Darnella Frazier via Facebook, shows a Minneapolis, Minnesota, police officer arresting George Floyd.

This still image taken from a 25 May video with permission, shows a Minneapolis, Minnesota, police officer arresting George Floyd. Photo: AFP / Facebook / Darnella Frazier

Minnesota’s US attorney Erica McDonald pledged a “robust and meticulous investigation” of Floyd’s arrest and death.

The federal investigation, which Attorney General William Barr had designated a “top priority,” will focus on whether the arresting officers used the “colour of law” to deprive Floyd of his civil rights, she said.

Floyd, a Houston native known affectionately to friends as “Big Floyd” and who had worked as a nightclub security staffer, was suspected of trying to pass counterfeit money at a corner store when police took him into custody. An employee who called for help described the suspect as appearing to be drunk, according to a police transcript of the call.

Sympathy protests erupted on Wednesday in Los Angeles and Thursday in Denver, with hundreds of demonstrators blocking freeway traffic in both cities.

Thursday night’s unrest in Minneapolis reportedly spread into adjacent city of St Paul, the Minnesota state capital.

-Reuters