CHARLOTTESVILLE, UNITED STATES (AFP) - The FBI said it has opened a civil rights investigation into the circumstances that led a driver to plow a car into a crowd while white nationalist activists and counter-protesters clashed in Charlottesville on Saturday (Aug 12).

The car ramming killed a 32-year-old woman and wounded 19 people, including some with life-threatening injuries.

Attorney General Jeff Sessions, the top law enforcement official in the country, said “the violence and deaths in Charlottesville strike at the heart of American law and justice”.

Sessions said he had spoken with FBI Director Chris Wray, along with FBI agents on the scene and law enforcement officials from Virginia, the state home to Charlottesville.

“The Richmond FBI Field Office, the Civil Rights Division and the US Attorney’s Office for the Western District of Virginia have opened a civil rights investigation into the circumstances of the deadly vehicular incident that occurred earlier Saturday morning,” they said in a statement.

Part of what made the case become a federal one was that the chief suspect, 20-year-old James Alex Fields Jr crossed state lines, travelling from Ohio to Virginia. Fields is in police custody.

Three others have also been arrested in relation to the clashes.

President Donald Trump has come under fire, including from fellow Republicans, for his apparent refusal to criticise far-right hate groups.

Senator Ted Cruz, who lost a campaign to become the Republican presidential nominee, has called for the Justice Department to investigate and prosecute the incident as an “act of domestic terrorism”.

“Absolutely we are going to have further demonstrations in Charlottesville, because our constitutional rights are being denied,” said Jason Kessler, identified by civil rights groups as a white nationalist blogger. He did not specify when.

Kessler organised the “Unite the Right” rally in Charlottesville against a plan to remove a statue to Confederate war hero Robert E. Lee from a park, saying in a telephone interview those who came in support will not back down.