The incident happened on Monday night in Kittrell, a small North Carolina town of less than 500 people located south of the Virginia border.
Vance County sheriff's deputies responded to an address there after getting a call about a fight, Sheriff Peter White said.
White said Lloyd Woodlief, 84, had initially wounded his 49-year-old son Lloyd Peyton Woodlief with a .22-caliber gun before the unidentified boy fired a shotgun at his grandfather.
While Lloyd Woodlief died at the scene, his son is being treated at Duke Medical Center in Durham, CNN reported.
Charges are pending, the sheriff added, though he did not specify who might be charged, or for what, the report said.