McDuffie County Coroner Rhusha Mack said Michael Dingus was pronounced dead at 10:23 a.m.
GBI special agent Pat Morgan said that McDuffie County dispatchers received a call about 9:20 a.m. and that authorities from McDuffie and Columbia counties and the Georgia State Patrol responded to the 1400 block of Jean Road.
"It appears that two juveniles were away from the home down near a pond and one of them was shot," Morgan said shortly after noon. "We're not ruling out anything at this point."
Morgan later said the other boy, who was 13, shot the 12-year-old in the chest with some sort of rifle.
Police are still trying to determine whether the shooting was accidental. The victim will undergo an autopsy today.
Morgan said officers answering the call intercepted a vehicle with the victim in it at the intersection of Jean and Smith Crawford roads.
The GBI was later called.