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.

"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," the Federal Bureau of Investigation's Richmond Division said in a statement.

"The FBI will collect all available facts and evidence."

Three other people were arrested in connection with the violence, CNN reported, though it was not clear whether they had a connection to the deadly car crash.