Authorities said 19 other pedestrians suffered injuries ranging from serious to minor.

As a girl, Ms Heyer stood up for people being picked on while riding on the school bus.

On Saturday, she was killed standing up for her country, according to a childhood friend.

Ms Heyer was among those gathered in Charlottesville to oppose neo-Nazis, Ku Klux Klan members and other white nationalists who were protesting against the removal of a Confederate statue.

"People will remember her name and remember what she died for," said the friend, Felicia Corr

An Ohio man was charged with second-degree murder after police said the Dodge Challenger he was driving "at a high rate of speed" rear-ended another car and pushed vehicles into a crowd of pedestrians.

Police say the driver of the Challenger, James Alex Fields jnr, 20, fled the scene. He also was charged with three counts of malicious wounding and one count of hit-and-run.

Charlottesville city officials said in a statement on Sunday that Ms Heyer "was struck down by a vehicle while exercising her peaceful first-amendment right to speech. This senseless act of violence rips a hole in our collective hearts."

Ms Correa said she recently was swamped with medical bills after complications related to her multiple sclerosis, so she went to a Charlottesville law firm. When Ms Heyer, who was working as a paralegal there, walked out to meet her she was ecstatic to see the friend she had known growing up in Greene County, Virginia.

 Ms Heyer jumped in and guided Ms Correa, who was uninsured and is a mother of six, through the daunting financial process.

Ms Heyer was a "young white woman who died standing up not just for people of colour in general but, also the people of colour that I love, that I worry about," said Ms Correa, who is biracial.

"She died for a reason. I don't see any difference in her or a soldier who died in war. She, in a sense, died for her country. She was there standing up for what was right.

"I just want to make sure that it wasn't in vain."

US President Donald Trump was under fire on Sunday for what critics said was his weak response to the protests.

Mr Trump refused to single out the white nationalist movement at the centre of the protests, instead criticising violence "on may sides."

The picture emerging of Ms Heyer contrasted to that of the man allegedly responsible for her death.

The accused driver, James Alex Fields jnr, was reportedly well known for his Nazi sympathies, according to Derek Weimer, who taught Fields history at Randall K. Cooper High School in Kentucky.

"It was obvious that he had this fascination with Nazism and a big idolatry of Adolf Hitler," Mr Weimer said. "He had white supremacist views. He really believed in that stuff."

"When you're a teacher and you see one of your former students do this, it's a nightmare scenario.

"This was something that was growing in him. I admit I failed. I tried my best. But this is definitely a teachable moment and something we need to be vigilant about because this stuff is tearing up our country."

Video recorded at the scene of the crash shows the 2010 Dodge Challenger accelerating into crowds on a pedestrian mall, sending bodies flying – and then reversing at high speed, hitting more people.

Witnesses said the street was filled with people opposed to the white nationalists, who had come to town bearing Confederate flags and anti-Semitic epithets.

Brian Moran, Virginia secretary of public safety, described the incident as a terrorist attack.

The FBI field office in Richmond and the US Attorney's Office in the Western District of Virginia said late on Saturday that they had opened a civil rights investigation into the deadly crash.

"The violence and deaths in Charlottesville strike at the heart of American law and justice," US Attorney General Jeff Sessions said in a statement.

"When such actions arise from racial bigotry and hatred, they betray our core values and cannot be tolerated."

Records show Fields last lived in Maumee, Ohio, south-west of Toledo.

His father was killed by a drunk driver a few months before the boy's birth, according to an uncle who spoke on the condition of anonymity. His father left him money that the uncle kept in a trust until Fields reached adulthood.

"When he turned 18, he demanded his money, and that was the last I had any contact with him," the uncle said.

Fields, he said, grew up mostly in Northern Kentucky, where he'd been raised by a single mother who was a paraplegic. 

Richard Spencer, a leader in the white supremacist movement who coined the term "alt-right," said he didn't know Fields but had been told he was a member of Vanguard America, which bills itself as the "Face of American Fascism."

In a statement tweeted on Saturday night, the group denied any connection to Fields.

In several images that circulated online, he was photographed with the group while wearing its unofficial uniform. Like members, he was dressed in a white polo, baggy khakis and sunglasses, while holding a black shield that features a common Vanguard symbol.

"The shields seen do not denote membership, nor does the white shirt," the group said in its statement. "The shields were freely handed out to anyone in attendance."

Vanguard members did not respond to requests for comment on Sunday.

Also on Saturday, two state police officers died when their helicopter crashed on the outskirts of town. Berke M.M. Bates, 40, of Quinton, Virginia, was the pilot, and H. Jay Cullen, 48, of Midlothian, Virginia, was a passenger, according to officials.

On Sunday morning, one day after Virginia Governor Terry McAuliffe declared a state of emergency, he and Lieutenant Governor Ralph Northam attended a service at Mount Zion First African Baptist Church.

The Governor brought the predominantly African American congregation to its feet as he stood at the pulpit and condemned "the white supremacists and neo-Nazis who came to our state yesterday."

"You pretend you're patriots. You are not patriots. You are dividers," he said, then later, his voice roaring: "Shame on you!"

At the church service, Gov. McAuliffe said he was close to both of the officers who had died.

Their deaths, he said, had enraged him, but he'd tried to move beyond that emotion and asked the congregation to do the same.

"Let us use today to reach out to our fellow citizens, put your hand out to help them," he said. "Let us show these people that we are bigger than them, we are stronger than them."

Saturday's 'Unite the Right' rally was meant to be a protest against the planned removal of a statue of Confederate General Robert E. Lee. The city of Charlottesville voted to remove the statue earlier this year, but it remains in Emancipation Park, formerly known as Lee Park, pending a judge's ruling expected later this month.​

Naundi Cook, 23, who is black, said that she came to Saturday's counter-protests to "support my people" but that she had never seen something like this before.

When violence broke out, she started shaking and got goose bumps.

"I've seen people walking around with tear gas all over their face, all over their clothes. People getting Maced, fighting," she said. "I didn't want to be next."

Ms Cook said she couldn't sit back and watch white nationalists descend on her town. She has a three-year-old daughter to stand up for, she said.

"Right now, I'm not sad," she said once the protests dispersed. "I'm a little more empowered. All these people and support, I feel like we're on top right now because of all the support that we have."

The Washington Post