CHARLOTTESVILLE: 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.