Three people were killed on Friday in an ostensible robbery at the Lock Stock & Barrel Shooting Range in Grantville, Georgia, according to local police officials.

The shooting occurred around 5:30 p.m., the Grantville Police Department said in an official 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 told. Around 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 observing 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 supporting it.

Authorities are asking anyone that drove by the shooting range between 5:30 p.m. and 6:30 p.m. on Friday, who may have seen vehicles other than a white Ford dual-rear-wheel truck and a black Ford Expedition, to contact them.

The ATF, City of Grantville, and National Shooting Sports Foundation have announced a combined reward of up to $15,000 for information leading to the arrest and conviction of those responsible for the triple murder, armed robbery, and theft of firearms from the shooting range, the ATF said in a news release.

ATF is offering a payment of up to $5,000, which will be matched by the City of Grantville and NSSF for a total of up to $15,000, the release said.