A white nationalists' rally erupted into deadly violence Saturday as a car rammed into a crowd while demonstrators and counter-protesters clashed, spurring President Donald Trump to condemn "hatred, bigotry and violence on many sides."

But as the death toll linked to the rally rose to three — one in the car ramming and two state police officers in a helicopter crash outside Charlottesville — the president's apparent refusal to criticize far-right hate groups sparked sharp criticism, even from members of his Republican Party.

Virginia Governor Terry McAuliffe had already declared a state of emergency when a sedan surged into a crowd of what witnesses said was counter-demonstrators in the picturesque university city of Charlottesville. A 20-year-old man was in custody over the attack.

A 32-year-old woman was killed and 19 were hurt, police said, with injuries ranging from minor to life-threatening.

Another 16 people were treated for other injuries linked to the rally, including from "individual engagements," Charlottesville police chief Al Thomas said.

The cause of the helicopter crash, which occurred in a nearby wooded area, was under investigation, Virginia State Police said. There was no indication of foul play.

Lieutenant H. Jay Cullen and Trooper-Pilot Berke M.M. Bates had been assisting law enforcement efforts with the situation in Charlottesville, the agency said.

Trump tweeted his "deepest condolences to the families & fellow officers of the VA State Police who died today."

He later added: "Condolences to the family of the young woman killed today, and best regards to all of those injured, in Charlottesville, Virginia. So sad!"

Hundreds had descended on Charlottesville either to march in or rail against a "Unite the Right Rally." Unrest quickly flared even as riot police and national guard troops flooded the city's downtown.

White far-right supporters, some wearing hats with Trump's "Make America Great Again" slogan and others in riot gear with shields and batons, faced off against counter-protestors as each side hurled projectiles before overwhelming the police positioned between them.

State police swooped in with tear gas as one counter-protestor who was repeatedly pummelled with sticks and a metal pole was left bleeding profusely.

Many of the far-right supporters brandished Confederate battle flags, considered a symbol of racism by many Americans, while others raised their arms in Nazi salutes.

Anti-racism protesters waved flags from the Black Lives Matter movement, chanting slogans like "We say no to racist fear."

Page 1 of 2