South Carolina will seek the death penalty for Dylann Roof, who is charged with the June murders of nine black worshippers at a Charleston church, a state prosecutor said on Thursday.

The 21-year-old Roof, who is white, has been accused of gunning down his victims, members of a Bible study group at Charleston's Emanuel AME Church, because it was a nationally known historically black church.

"This was the ultimate crime and justice from our state calls for the ultimate punishment," Ninth Judicial Circuit Solicitor Scarlett Wilson said at a news conference.