Rainwater would not name the make and model of the airplane, pointing out that next of kin had not yet been notified.
Early Saturday evening, he said officers were waiting for officials with the National Transportation Safety Board to arrive and take control of the investigation.
Channel 2 Action News reporter Christian Jennings reported that federal officials were on the scene as night approached.
The area of the crash is residential, with houses on one side of the road and Lake Lanier on the other.
Rainwater said many passers-by were on hand to help the victims immediately after the plane crash, which caused a small fire.