CHARLOTTESVILLE, Va. (Reuters) - A gathering of hundreds of white nationalists in Virginia took a deadly turn on Saturday when a car plowed into a group of counter-protesters and killed at least one person in a flare up of violence that challenged U.S. President Donald Trump.

The state’s governor blamed neo-Nazis for sparking the unrest in the college town of Charlottesville, where rival groups fought pitched battles using rocks and pepper spray after far-right protesters converged to demonstrate against a plan to remove a statue to a Confederate war hero.

A car slammed into a crowd of people, killing a 32-year-old woman, police said. Video on social media and Reuters photographs showed the car hit a large group of counter-protesters, sending some flying into the air.

Federal authorities opened a civil rights investigation into the death.

Two Virginia policeman died in a helicopter crash nearby after assisting efforts to quell the clashes.

Virginia Governor Terry McAuliffe, a Democrat, declared an emergency and halted a white nationalist rally, while President Donald Trump condemned the violence.

“I have a message to all the white supremacists and the Nazis who came into Charlottesville today. Our message is plain and simple: go home,” McAuliffe told a news conference.

“You are not wanted in this great commonwealth. Shame on you.”

As midnight approached, the streets of Charlottesville had gone quiet.

The clashes highlight how the white supremacist movement has resurfaced under the “alt-right” banner after years in the shadows of mainstream American politics.

Trump said “many sides” were involved, drawing fire from across the political spectrum for not specifically denouncing the far right. The violence presented Trump with perhaps the first domestic crisis of his young administration.

“We’re closely following the terrible events unfolding in Charlottesville, Virginia,” Trump told reporters at his New Jersey golf course.

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

Trump made no reply to a reporter’s shouted question whether he had spoken out strongly enough against white nationalists.

Police held a man from Ohio on charges relating to the car incident, including second-degree murder, said Martin Kumer, Albemarle Charlottesville’s regional jail superintendent.

The suspect was James Alex Fields, Jr., a 20-year-old white man from Ohio, Kumer said. It was not clear why he was in Charlottesville, home to the University of Virginia’s flagship campus.

After hours of clashes, a silver sedan driving at high speed plowed into the crowd before reversing along the same street. The incident took place about two blocks from the park displaying the statue of Robert E. Lee, who headed the Confederate army in the American Civil War.

Five people suffered critical injuries and four had serious injuries from the car strike, officials said.

A civil rights investigation has been opened into the crash death, the U.S. Attorney’s Office for the Western District of Virginia and the FBI’s Richmond field office said late on Saturday.

“The FBI will collect all available facts and evidence,” they said in a joint statement.

Attorney General Jeff Sessions also condemned the violence in Charlottesville, vowing “the full support of the Department of Justice” for the U.S. Attorney’s office in a statement.

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Three more men were arrested, Virginia State Police said late on Saturday night. Two 21-year-olds from Tennessee and Virginia were charged, one with disorderly conduct and the other with assault and battery, while a 44-year-old Florida man was arrested for carrying a concealed weapon.

‘DOMESTIC TERRORISM?’

Prominent Democrats, civil rights activists and some Republicans said it was inexcusable of the president not to denounce white supremacy.

“Mr. President - we must call evil by its name,” Republican U.S. Senator Cory Gardner wrote on social network Twitter.

“These were white supremacists and this was domestic,” said Gardner, chairman of the National Republican Senatorial Committee, the group charged with helping to get Republicans elected to the Senate.

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Nancy Pelosi, the Democratic leader in the U.S. House of Representatives, said in a tweet directed at the president: “Repeat after me, @realDonaldTrump: white supremacy is an affront to American values.”

Fighting broke out on Saturday in the city’s downtown, when hundreds of people, some wearing white nationalist symbols and carrying Confederate battle flags, were confronted by a nearly equal number of counter-protesters.

The Charlottesville City Council voted unanimously to allow the police chief to declare a curfew. No action on the move has been taken as midnight approached, Mayor Mike Signer said on his Facebook page.

The confrontation was a stark reminder of the growing political polarization since Trump’s election last year.

“You will not erase us,” chanted a crowd of white nationalists, while counter-protesters carried placards that read: “Nazi go home” and “Smash white supremacy.”

Scott Stroney, 50, a catering sales director at the University of Virginia who arrived at the scene of the car incident just after the crash, said he was horrified.

“I started to cry. I couldn’t talk for a while,” he said. “It was just hard to watch, hard to see. It’s heartbreaking.”

The violence began on Friday night, when hundreds of white marchers with blazing torches appeared at the campus in a display that critics called reminiscent of a Ku Klux Klan rally.

David Duke, a former leader of the white supremacist Ku Klux Klan, was in Charlottesville for the rally, according to his Twitter account.

The rally was part of a long debate in the U.S. South over the Confederate battle flag and other symbols of the rebel side in the Civil War, which was fought over the issue of slavery.

The violence is the latest clash between far-rightists, some of whom have claimed allegiance to Trump, and the president’s opponents since his January inauguration, when black-clad anti-Trump protesters in Washington smashed windows, torched cars and clashed with police, leading to more than 200 arrests.

About two dozen people were arrested in Charlottesville in July when the Ku Klux Klan rallied against the plan to remove the Lee statue. Torch-wielding white nationalists also demonstrated against the decision in May.