A Minneapolis policeman accused of killing unarmed African-American man George Floyd by kneeling on his neck was taken into custody on Friday and charged with third-degree murder.

Death of 46-year-old George Floyd who was arrested on suspicion of using a counterfeit banknote on Monday has sparked protests in Minnesota and other cities across US.

A video taken by a bystander shows an officer, identified as Derek Chauvin kneeling on his neck as he is pinned to the ground. Floyd who was unarmed and handcuffed, pleaded that he could not breathe. He was soon after declared dead at a nearby hospital on Monday.

Chauvin is one of four officers who were fired shortly after the explosive video emerged showing Chauvin pinned his knee to Floyd’s neck for at least five minutes on Monday.

“Former Minneapolis police officer Derek Chauvin is in custody,” Hennepin county prosecutor Mike Freeman told reporters.

“Chauvin has been charged… with murder and with manslaughter,” he added, specifying to reporters that the charge was third-degree murder.

US Senator Amy Klobuchar of Minnesota applauded Chauvin’s arrest, calling it “the first step towards justice.”

During protests, so far, hundreds of shops have been damaged and a police station set on fire.

Protests swelled after federal authorities said Thursday that they were making the case a top priority but announced no arrests at that time.

Overnight, demonstrators broke through law enforcement barriers to overtake the Minneapolis police station where the four officers blamed for Floyd’s death were based.

Four policemen involved in the incident have been suspended, while the FBI is investigating the case.

The protests entered their fourth day on Friday and have spread beyond Minnesota, with protests breaking out in several states across the country, including Denver, Colorado and Phoenix.

The case was seen as the latest example of police brutality against African Americans, which gave rise six years ago to the Black Lives Matter movement.

Floyd had been detained on a minor charge of allegedly using a counterfeit $20 bill to make a purchase at a convenience store.

Outbreaks of violence have gripped the city as tensions rose since Floyd’s killing.

The protests were reminiscent of those that followed the 2017 death of Philando Castile, who was sitting in his car after a traffic stop in a nearby suburb when an officer shot him.

US President Donald Trump on Friday said that he has spoken with the family of George Floyd, the African American man who died when a policeman kneeled on his neck during an arrest that sparked riots.

Trump said at the White House, “I spoke to members of the family, terrific people”.

As unrest spread, President Trump had earlier tweeted: “These THUGS are dishonouring the memory of George Floyd and I won’t let that happen,” in apparent reference to protesters in Minnesota, adding the state’s governor has the backing of the military. “Any difficulty and we will assume control but, when the looting starts, the shooting starts.”