The incident occurred at about 5 p.m. on the Goliath ride at the park in Austell, about 25 kilometres north-west of Atlanta, according to the Cobb County Police Department and local media. The park said its staff and local authorities responded immediately and that it was providing support to affected guests and employees.
"We are deeply saddened by the guest incident at our park today," Six Flags Over Georgia said in a statement. "Our thoughts and heartfelt condolences are with the guest's family, friends, and loved ones."
The statement did not explain how the accident happened or identify the person who died. The park said it was "cooperating fully with local authorities as they complete their investigation" and would not share additional details out of respect for the family's privacy.
Witnesses who spoke to NBC affiliate WXIA of Atlanta said they saw a man fall from the ride, with at least two saying he struck parts of it multiple times before hitting the ground. Officials have not confirmed how the person died or what caused the others to be injured, and it is not clear whether the four people taken to hospital also fell from the ride or were hurt another way.
One witness who posted on Reddit described the moments the train returned to the station: "All the riders were distressed, and a man who was sitting next to the seat that failed was screaming that whoever was sitting next to him fell out. The seats restrain was completely unlatched and unlocked with no one in the seat."
Goliath opened in 2006 and reaches speeds of up to 70 miles per hour, with a first hill rising 200 feet, according to Six Flags. Riders were evacuated from the ride after the accident, and the park was closed for the day. Detectives from the Cobb County Police Department's major crimes unit are investigating.