Top pop stars including Ariana Grande, Justin Timberlake and Pharrell Williams on Wednesday announced a unity concert in Charlottesville in the wake of a violent white supremacist rally.

Promoters said that the September 24 concert at the University of Virginia's Scott Stadium would be free, although they encouraged donations.

The funds will support people affected by the violence as well as "organizations devoted to the promotion of healing, unity and justice locally and nationwide," a concert announcement said.

The Dave Matthews Band -- the Charlottesville-rooted jam rock band known for its left-leaning activism despite its broad-based fan base -- will serve as the concert's host and headliner.

Other acts include hip-hop ensemble The Roots, country star Chris Stapleton, garage rockers Cage the Elephant and Brittany Howard, the powerful voice of bluesy rockers Alabama Shakes.

The usually idyllic Virginia college town became the center of an international outcry on August 12 when neo-Nazis, Ku Klux Klan supporters and other white supremacists openly marched in town.

Heather Heyer, who was taking part in the large counter-demonstration, was killed when a far-right supporter ran his car into the crowd.

President Donald Trump, who has championed a hard line on immigration, stunned even some of his political allies when he insisted there were "very fine people" on both sides in Charlottesville.

The concert is the latest star-studded show this year in response to a tragedy.

Pop superstar Beyonce and Hollywood A-listers including George Clooney will take part in a televised special on September 12 for victims of massive storm Harvey.

On June 4, Grande led a who's who of pop stars in the One Love Manchester benefit concert after 22 people were killed and 250 injured at one of her concerts in the English city in a suicide bombing by a supporter of the Islamic State group.