Donald Trump fans the flames of hate as police officer charged with George Floyd's murder

One of four cops named in connection with George Floyd’s death was tonight charged with murder – as protesters torched their HQ and Donald Trump threatened violence.

Rather than appeal for calm, the President vowed to unleash hell against thousands of demonstrators growing increasingly angry over the death of yet another black person in custody.

As US cities boiled over, demanding justice for Mr Floyd, Trump was accused of glorifying violence by Twitter for posting: “When the looting starts, the shooting starts.”

The US leader fanned the flames of tensions as dozens of buildings were razed to the ground in the third night of unrest which has left Minneapolis, Minnesota, looking like a war zone.

The protests had come before the sacked officer who allegedly knelt on the neck of Mr Floyd was today arrested.

Derek Chauvin, 44, who has already been fired, was charged with third-degree murder and manslaughter.

It also emerged he and Mr Floyd had known each other for “many years” as they worked security at the same night club, according to Minneapolis City Council vice president Andrea Jenkins.

The arrest news came too late to prevent the violence which the Mirror witnessed unfolding, as demonstrators stormed the Third Police Precinct, their anger taking on a renewed energy as Trump called them “thugs”.

His Twitter post was quickly marked with a warning by the social media company as they labelled accompanying comments “glorifying violence”.

500 National Guard soldiers were deployed as the President threatened to “assume control”.

Violence flared on Thursday night when news broke that officers allegedly involved in Mr Floyd’s fatal detainment – Chauvin, Thomas Lane, Tou Thao and J. Alexander Kueng – had not been arrested.

Quickly, hundreds had again converged on the station the four police had been based at.

At around 10pm, the Mirror watched as dozens of officers were forced to flee the Third Police Precinct as groups of angry protesters stormed the building.

The station had been under siege since Mr Floyd’s death on Monday, but protected by armed police. Officers escaped when demonstrators forcibly entered and “ignited several fires,” police spokesman John Elder said.

Mayor Jacob Frey said he decided to pull police out of the precinct.

“You know brick and mortar is not as important as life,” he said. City officials had pleaded with people to “retreat” from the area as a precaution.

“We’re hearing unconfirmed reports that the gas lines to the Third Precinct have been cut and other explosive materials are in the building,” their Twitter feed read.

One of the protesters who had stormed the building told me the interior had been stripped bare and that fires were set on “every level”.

“F*** the police,” he said, giving his name only as TJ. “They no longer run this city. We do. We’re taking back what is ours and what they’ve taken from us. It’s George Floyd now, but who will it be next month? No longer are we going to be casualties.”

As the station burned, elsewhere demonstrators descended on the Minneapolis Police Department’s Fourth Precinct to the north-west.

Hundreds of police in body armour and riot gear were drafted in from across the state, joining the National Guard to line the streets in a bid to take back control.

Gone was the tear gas that filled Thursday night’s air. In its place was billowing black smoke and water from the hoses of countless fire engines. More than 170 businesses were damaged or looted, the city’s police department said yesterday.

Police had sparked global criticism after they arrested a CNN news crew live on-air leading the UK Foreign Office to say journalists “must be free to do their job”. The channel’s Omar Jimenez, producer Bill Kirkos and photojournalist Leonel Mendez were held in Minneapolis at around 5am.

From New York City to Los Angeles, protesters have taken to the streets across the States demanding justice for Mr Floyd. At least seven people were shot in Louisville, Kentucky, as hundreds of protesters there converged on City Hall.

Mr Floyd was arrested after he allegedly used a fake $20 bill at a store in South Minneapolis on Monday.

Surveillance video from outside a nearby restaurant appears to contradict police claims he resisted arrest.

Outrage grew after a video surfaced showing officer Chauvin kneeling on his neck for eight minutes during the arrest. Mr Floyd was unarmed and handcuffed, and pleaded he couldn’t breathe before he later died. More damning video emerged yesterday.

Trump had tweeted: “A total lack of leadership. Either the very weak Radical Left Mayor, Jacob Frey, get his act together and bring the city under control, or I will send in the National Guard & get the job done right.

"There THUGS are dishonouring George Floyd... Any difficulty and we will assume control but, when the looting starts, the shooting starts.”