Police in riot gear keep protesters at bay in Lafayette Park near the White House in Washington on Sunday. Jonathan Ernst/Reuters

Fires burned near the White House, stores were looted in New York City and Southern California, and a tanker truck drove into marchers in Minneapolis as the United States struggled to contain chaotic protests over race and policing.

National Guard troops were deployed in 15 states and Washington, D.C. in an attempt to quell a sixth night of violence on Sunday. The unrest began with peaceful protests over the death of a black man, George Floyd, in police custody.

Video footage showed a white Minneapolis police officer, Derek Chauvin, kneeling on the neck of Floyd, 46, for nearly nine minutes before he died on May 25.

His death caused outrage across a nation that is politically and racially divided during a polarising presidential campaign.

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De Blasio said he had not seen a separate video showing an officer pulling down the mask of a black protester to spray something in his face.

Among those arrested for unlawful assembly on Saturday night was de Blasio's 25-year-old daughter, Chiara, according to a New York Police Department source, who said she was issued a "desk appearance ticket" and released.

Police fired tear gas outside the White House late on Sunday as anti-racism protestors again took to the streets to voice fury at police brutality, and major US cities were put under curfew to suppress rioting.

A protester throws a US flag into a burning barricade during a demonstration near the White House on Sunday. AFP

Secret Service agents rushed President Donald Trump to an underground bunker on Friday, as hundreds of protesters gathered outside the White House, some throwing rocks and tugging at police barricades just outside the executive mansion.

That’s according to a Republican close to the White House not authorised to publicly discuss private matters and confirmed by another official. The abrupt decision by the agents underscored the rattled mood inside the White House, where the chants from Lafayette Park could be heard all weekend and Secret Service agents and law enforcement officers struggled to contain the crowds.

"I hate to see my city like this but at the end we need justice," said 18-year-old Jahvon Craven as he stood on an overpass watching protesters below on Interstate 35 in downtown Minneapolis moments before an 8pm curfew went into effect.

Protesters are thugs: Trump
Authorities imposed curfews on dozens of cities across the United States, the most since the aftermath of the assassination of Martin Luther King Jr in 1968 -- also during an election campaign and in the upheaval of anti-war demonstrations.

President Donald Trump has described the current protesters as "thugs". "Get tough Democrat Mayors and Governors," Trump, a Republican, said on Twitter on Sunday afternoon. "These people are ANARCHISTS. Call in our National Guard NOW."

But Trump's administration will not take control of the National Guard for now, national security adviser Robert O'Brien said.

In Washington, DC, protesters set fires near the White House on Sunday. The smoke mixed with billowing clouds of tear gas as police sought to clear from the area crowds chanting "George Floyd".

Sporadic violence broke out in Boston following peaceful protests as activists threw bottles at police officers and lit a cruiser on fire. Philadelphia announced a 6 pm to 6 am curfew.

People march along Colfax Avenue during the aftermath of the death of George Floyd on May 31 in Denver, Colorado. AFP

On Sunday afternoon, a tanker truck drove into demonstrators on the I-35 highway in Minneapolis, which had been closed to traffic. The driver was pulled from the cab and beaten by protesters before police took him into custody. It did not appear any protesters were hit by the truck.

On the West Coast, there were also clashes in Portland, Oregon, where TV footage showed small fires burning as police fired tear gas at protesters who set off fireworks.

In Santa Monica, California, upscale stores were looted along the city's popular Third Street Promenade before police moved in to make arrests. The vandalism followed a largely peaceful march.

Further south, in the Los Angeles suburb of Long Beach, a group of young men and women smashed windows of a shopping mall and looted stores before they were dispersed before a 6 pm curfew.

The demonstrations brought out a diversity of people.

"It means a lot to see people other than black people joining the demonstration," said Candace Collins, a young black woman at a march in Culver City, California.

Thousands of people gathered peacefully on Sunday afternoon for a rally in St. Paul, adjacent to Minneapolis, as state troopers surrounded the state capitol building. About 170 stores in the city have been looted, its mayor told CNN.

Protests have also flared in Chicago, Seattle, Salt Lake City, Cleveland and Dallas, where rioters were seen on video beating a store owner who chased them with a large machete or sword. Police said on Sunday he was in stable condition.

On Sunday, the Justice Department also deployed members of the US Marshals Service and agents from the Drug Enforcement Administration to supplement National Guard troops outside the White House, according to a senior Justice Department official. The official could not discuss the matter publicly and spoke on condition of anonymity.

With the Trump administration branding instigators of six nights of rioting as domestic terrorists, there were more confrontations between protesters and police and fresh outbreaks of looting.

One closely watched protest was outside the state capitol in Minneapolis' twin city of St. Paul, where several thousand people gathered before marching down a highway.

"We have black sons, black brothers, black friends, we don't want them to die. We are tired of this happening, this generation is not having it, we are tired of oppression," said Muna Abdi, a 31-year-old black woman who joined the protest.

Hundreds of police and National Guard troops were deployed ahead of the protest.

Washington's mayor ordered a curfew from 11pm until 6am.

Gucci, Rolex stores ransacked

Looting was reported on Sunday night in Philadelphia and the Los Angeles suburb of Santa Monica, and images on Fox TV showed ransacked Rolex and Gucci stores in New York City.

Officials in LA -- a city scarred by the 1992 riots over the police beating of Rodney King, an African-American man -- imposed a curfew from 4pm on Sunday until dawn.

"Please, use your discretion and go early, go home, stay home," the city's mayor Eric Garcetti said on CNN.

Looters stand outside a jewellery store in downtown Long Beach during a protest on Sunday. AFP

Late Sunday, as many were being arrested for curfew violations in Minneapolis, authorities moved Chauvin to another location from the Hennepin County Jail for his own safety, according to Minnesota's corrections commissioner.

Three other officers with him at the arrest have been fired but for now face no charges.

Governor Tim Walz has mobilised all of Minnesota's National Guard troops -- the state guard's biggest mobilisation ever -- to help restore order and extended a curfew for a third night Sunday.

Trump blamed the extreme left for the violence, saying he planned to designate a group known as Antifa as a terrorist organisation.

Protests spread around the globe, with events in London and Berlin on Sunday and others on Monday including in New Zealand, Australia and the Netherlands.

Agencies