The 18-year-old gunman who authorities say killed 10 people at a Buffalo supermarket had previously threatened a shooting at his high school and was sent for mental health treatment.
Hundreds of people have gathered in a park across from the Georgia state Capitol in Atlanta to demand justice for the victims of shootings at massage businesses days earlier.
Clark Perry Baldwin, 59, of Waterloo, Iowa, was arrested by agents with the Wyoming Division of Criminal Investigation and Federal Bureau of Investigation.