Several people were injured after a car plowed into a crowd at a white nationalist rally in the US state of Virginia.

A car rammed into a crowd of protesters and a state police helicopter crashed into the woods as tension boiled over at a white supremacist rally.

The violent day left three dead, dozens injured and this usually quiet college town a bloodied symbol of the nation's roiling racial and political divisions.

The chaos erupted around what is believed to be the largest group of white nationalists to come together in a decade - including neo-Nazis, skinheads, members of the Ku Klux Klan - who descended on the city to "take America back" by rallying against plans to remove a Confederate statue.

JOSHUA ROBERTS/REUTERS Members of white nationalists are met by a group of counter-protesters in Charlottesville, Virginia.

Hundreds came to protest against the racism on Saturday (Sunday NZ Time). There were street brawls and violent clashes; the governor declared a state of emergency, police in riot gear ordered people out and helicopters circled overhead.

READ MORE: Clash on eve of white supremacy rally in Charlottesville

JOSHUA ROBERTS/REUTERS A white supremacists carries the Confederate flag as he walks past counter demonstrators in Charlottesville, Virginia.

Peaceful protesters were marching downtown, carrying signs that read "black lives matter" and "love." A silver Dodge Challenger suddenly came barrelling through "a sea of people" and smashed into another car, said Matt Korbon, a 22-year-old University of Virginia student.

The impact hurled people into the air and blew off their shoes. Heather Heyer, 32, was killed as she crossed the street.

"It was a wave of people flying at me," said Sam Becker, 24, sitting in the emergency room to be treated for leg and hand injuries.

JOSHUA ROBERTS/REUTERS A white supremacists stands with militia members after he scuffled with a counter demonstrator in Charlottesville, Virginia.

Those left standing scattered, screaming and running for safety. Video caught the car reversing, hitting more people, its windshield splintered from the collision and bumper dragging on the pavement. Medics carried the injured, bloodied and crying, away as a police tank rolled down the street.

The driver, James Alex Fields Jr, a 20-year-old who recently moved to Ohio from where he grew up in Kentucky, was charged with second-degree murder and other counts. Fields' mother, Samantha Bloom, told The Associated Press on Saturday night (Sunday NZT) that she knew her son was attending a rally in Virginia but didn't know it was a white supremacist rally.

"I thought it had something to do with Trump. Trump's not a white supremacist," said Bloom, who became visibly upset as she learned of the injuries and deaths at the rally.

JOSHUA ROBERTS/REUTERS Virginia State Troopers stand under a statue of Robert E Lee before a white supremacists rally in Charlottesville, Virginia.

"He had an African-American friend so ...," she said before her voice trailed off. She added that she'd be surprised if her son's views were that far right.

His arrest capped off hours of unrest. Hundreds of people threw punches, hurled water bottles and unleashed chemical sprays. Some came prepared for a fight, with body armour and helmets. Videos that ricocheted around the world on social media showed people beating each other with sticks and shields.

Virginia Governor Terry McAuliffe and Charlottesville Mayor Michael Signer, both Democrats, lumped the blame squarely on the rancour that has seeped into American politics and the white supremacists who came from out of town into their city, nestled in the foothills of the Blue Ridge Mountains, home to Monticello, Thomas Jefferson's plantation.

"There is a very sad and regrettable coarseness in our politics that we've all seen too much of today," Signer said at a press conference. "Our opponents have become our enemies, debate has become intimidation."

Some of the white nationalists at the rally cited US President Donald Trump's victory after a campaign of racially-charged rhetoric as validation for their beliefs.

Trump criticised the violence in a tweet, followed by a press conference and a call for "a swift restoration of law and order."

"We condemn in the strongest possible terms this egregious display of hatred, bigotry and violence on many sides," he said.

The "on many sides" ending of his statement drew the ire of his critics, who said he failed to specifically denounce white supremacy and equated those who came to protest racism with the white supremacists.

We ALL must be united & condemn all that hate stands for. There is no place for this kind of violence in America. Lets come together as one! — Donald J. Trump (@realDonaldTrump) August 12, 2017 Am in Bedminster for meetings & press conference on V.A. & all that we have done, and are doing, to make it better-but Charlottesville sad! — Donald J. Trump (@realDonaldTrump) August 12, 2017

The Reverend Jesse Jackson noted that Trump for years questioned former US President Barack Obama's citizenship and his legitimacy as the first black president, and has fanned the flames of white resentment.

"We are in a very dangerous place right now," Jackson said. McAuliffe said at a press conference that he spoke to Trump on the phone, and insisted that the president must work to combat hate.

Trump said he agreed with McAuliffe "that the hate and the division must stop and must stop right now."

Attorney General Jeff Sessions announced late on Saturday (Sunday NZT) that federal authorities will pursue a civil rights investigation into the circumstances surrounding the crash.

The violence and deaths in Charlottesville strike at the heart of American law and justice," Sessions wrote. "When such actions arise from racial bigotry and hatred, they betray our core values and cannot be tolerated."

Oren Segal, who directs the Anti-Defamation League's Center on Extremism, said multiple white power groups gathered in Charlottesville, including members of neo-Nazi organisations, racist skinheads and KKK factions. The white nationalist organisations Vanguard America and Identity Evropa; the Southern nationalist League of the South; the National Socialist Movement; the Traditionalist Workers Party; and the Fraternal Order of Alt Knights also were on hand, he said.

"We anticipated this event being the largest white supremacist gathering in over a decade," Segal said. "Unfortunately, it appears to have become the most violent as well."

On the other side, anti-fascist demonstrators also gathered, but they generally aren't organised like white nationalist factions, said Heidi Beirich of the Southern Poverty Law Center.

In addition to Fields, at least three more men were arrested in connection to the protests.

The Virginia State Police announced that Troy Dunigan, a 21-year-old from Chattanooga, Tennessee, was charged with disorderly conduct; Jacob L Smith, a 21-year-old from Louisa, Virginia, was charged with assault and battery; and James M O'Brien, 44, of Gainesville, Florida, was charged with carrying a concealed handgun.

Just as the city seemed like to be quieting down, black smoke billowed out from the tree tops just outside of town as a Virginia State Police helicopter crashed into the woods.

Robby E Noll, who lives in the county just outside Charlottesville, heard the helicopter sputtering.

"I turned my head to the sky. You could tell he was struggling to try to get control of it," he said.

He said pieces of the helicopter started to break off as it fell from the sky.

Both troopers onboard, Lieutenant H Jay Cullen, 48, and Berke MM Bates, one day shy of his 41st birthday, were killed. Police said the helicopter had been deployed to the violent protests in the city, which has been caught in the middle of the nation's culture wars since it decided earlier this year to remove a statue of Confederate General Robert E Lee, enshrined in bronze on horseback in the city's Emancipation Park, formerly named Lee Park.

In May, a torch-wielding group that included prominent white nationalist Richard Spencer gathered around the statue for a nighttime protest, and in July, about 50 members of a North Carolina-based KKK group travelled there for a rally. Spencer returned for Saturday's protest, and denied all responsibility for the violence. He blamed the police.

Signer said the white supremacist groups who came into his city to spread hate "are on the losing side of history."

"Tomorrow will come and we will emerge," he said, "I can promise you, stronger than ever."

In neighbouring state Kentucky, the mayor of Lexington, hinted that the white supremacists might get the opposite of what they'd hoped for.

Mayor Jim Gray announced on Twitter that he would work to remove the confederate monument at his county's courthouse.

"Today's events in Virginia remind us that we must bring our country together by condemning violence, white supremacists and Nazi hate groups," he wrote. "We cannot let them define our future."

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