The shooting occurred around 5:30 p.m., the Grantville Police Department said in a statement on Facebook. Grantville is about 50 miles southwest of Atlanta.
Officers were dispatched to the range shortly after 8 p.m., where they found the owner, his wife and their grandson murdered, Grantville Police said. Approximately 40 weapons and a camera DVR were also taken from the scene, they added.
Officials did not specify how the three victims were killed.
The Georgia Bureau of Investigation is looking into the incident, the agency said to CNN in an email.
The Bureau of Alcohol, Tobacco, and Firearms (ATF) is involved in the investigation due to the number of weapons taken, police said. Members of the Coweta County Sheriff’s Department are also assisting.
Authorities are asking anyone that drove by the shooting range between 5:30 p.m. and 6:30 p.m., who may have seen vehicles other than a white Ford dual-rear-wheel truck and a black Ford Expedition, to contact them.