A 32-year-old woman was killed and dozens of others injured amid violent clashes between white supremacists and anti-fascists ahead of a rally protesting against the removal of a statue to a Confederate general in Charlottesville, Virginia.

A police helicopter also crashed, killing two people, with officials saying this was connected to the events on the ground, although it was unclear in what way.

A state of emergency was announced by the local and state governments with police declaring the "Unite the Right" rally an unlawful assembly and ordering the crowds to disperse. The state police were deployed, with riot police and the National Guard waiting in the wings.

Some of the far-right group members were seen carrying assault rifles and wearing paramilitary clothing, while others had large shields, helmets and gas masks in apparent anticipation of violence ahead of the demonstration against plans to take down the statue to General Robert E Lee from a local park.

The 32-year-old woman was killed when a car crashed at speed into anti-fascist protesters, leaving a crowd of people lying injured on the ground. Police said they had opened a homicide investigation.

Officials said the pilot of the police helicopter that crashed had been killed, along with a passenger. They said the crash was connected to the violence but it was unclear whether this was simply because the officers had been involved in the police operation or because of some other reason.

Police were investigating the cause of the crash, which happened while the aircraft was hovering low over some trees near a golf course.

Hospital officials said a total of at least 41 people had been hurt in the violence, including 26 as a result of the car crash and 15 others from the fighting in the streets. Some were said to have life-threatening injuries.

Graphic video showed a grey Dodge Challenger speeding up a side street into a group of people and crashing into another car.

Violence on the streets of Charlottesville Show all 9 1 /9 Violence on the streets of Charlottesville Violence on the streets of Charlottesville Protesters clash and several are injured White nationalist demonstrators clash with counter demonstrators at the entrance to Lee Park in Charlottesville, Virginia. A state of emergency is declared, August 12 2017 Violence on the streets of Charlottesville Trump supporters at the protest A white nationalist demonstrator walks into Lee Park in Charlottesville, Va., Saturday, Aug. 12, 2017. Hundreds of people chanted, threw punches, hurled water bottles and unleashed chemical sprays on each other Saturday after violence erupted at a white nationalist rally in Virginia. AP Photo Violence on the streets of Charlottesville State police stand ready in riot gear Virginia State Police cordon off an area around the site where a car ran into a group of protesters after a white nationalist rally in Charlottesville, Virginia AP Photo Violence on the streets of Charlottesville Militia armed with assault rifles White nationalists, neo-Nazis and members of the 'alt-right' with body armor and combat weapons evacuate comrades who were pepper sprayed after the 'Unite the Right' rally was declared a unlawful gathering by Virginia State Police. Militia members marched through the city earlier in the day, armed with assault rifles. Getty Images Violence on the streets of Charlottesville Statue of Confederate General Robert E Lee The statue of Confederate General Robert E. Lee stands behind a crowd of hundreds of white nationalists, neo-Nazis and members of the 'alt-right' during the 'Unite the Right' rally 12 August 2017 in Charlottesville, Virginia. They are protesting the removal of the statue from Emancipation Park in the city. Getty Images Violence on the streets of Charlottesville Racial tensions sparked the violence White nationalists, neo-Nazis and members of the 'alt-right' exchange insults with counter-protesters as they attempt to guard the entrance to Lee Park during the 'Unite the Right' rally Getty Violence on the streets of Charlottesville A car plows through protesters A vehicle drives into a group of protesters demonstrating against a white nationalist rally in Charlottesville, Virginia. The incident resulted in multiple injuries, some life-threatening, and one death. AP Photo Violence on the streets of Charlottesville Rescue personnel help injured people after a car ran into a large group of protesters after an white nationalist rally in Charlottesville, Virginia AP Photo Violence on the streets of Charlottesville President Donald Trump speaks about the ongoing situation in Charlottesville, Virginia from his golf club in Bedminster, New Jersey. He spoke about "loyalty" and "healing wounds" left by decades of racism.

Charlottesville police confirmed that a suspect, named as James Alex Fields Jr, 20, of Ohio, had been arrested. Officials said he was being held on charges including second-degree murder.

Earlier the two groups of protesters were involved in violent clashes with pepper spray — used, reportedly, by both sides — filling the air, according to local media reports. Bottles were also thrown and a number of fist fights broke out.

The city council voted to allow the police chief to declare a curfew.

Charlottesville Mayor Michael Signer, who confirmed one person had been killed, said he was disappointed the white nationalists had descended on his town and blamed Donald Trump for inflaming racial prejudices with his campaign last year.

"I'm not going to make any bones about it. I place the blame for a lot of what you're seeing in America today right at the doorstep of the White House and the people around the president," he said.

Mr Trump put out a tweet condemning "violence" and "hate" - although he did not specify that he was talking about the white supremacists, attracting criticism on Twitter. He later blamed hatred "on many sides" for the violence, prompting a furious backlash from some leading Republicans.

Earlier in the day apparent militia members were filmed marching through the streets armed with assault rifles and wearing tactical gear.

Other demonstrators were heard to chant the Nazi-linked phrase "blood and soil" as they passed through the streets.

And on Friday night neo-Nazi protesters brandishing flaming torches descended on the University of Virginia, brawling with counter-protesters and throwing Nazi salutes.

The state's governor, Terry McAuliffe, said on Friday: "Many of the individuals coming to Charlottesville ... are doing so in order to express viewpoints many people, including me, find abhorrent."

He urged people to stay away and "deny those ideas more attention than they deserve".

The clash was the latest in a series of confrontations after Charlottesville, situated about 100 miles from Washington DC, voted to remove the statue of General Lee.

Celebrating the Confederate cause is a highly inflammatory issue in the US because the southern states supported slavery.

In May, a torch-wielding group that included prominent white nationalist Richard Spencer gathered around the statue for a night-time protest, and in July, about 50 members of a North Carolina-based KKK group travelled there for a rally, where they were met by hundreds of counter-protesters.

Charlottesville is normally a quiet university city, and many of those protesting are believed to be from out of town.

“People are angry, they’re scared, they’re hurt, they’re confused,” said the Reverend Seth Wispelwey of the local United Church of Christ.

“White supremacists rallying in our town is an act of violence.”