KEENE VALLEY, N.Y. -- A 12-year-old boy and his uncle hiking in the Adirondacks were admiring the Roaring Brook Falls Sunday afternoon when a large rock fell and struck them, Essex County Coroner Frank Whitelaw said.

The boy died and his uncle was injured when the approximately 800- to 900-pound rock came loose and plummeted 25 to 30 feet, Whitelaw said.

"It was a freak accident," the coroner said.

The boy and his uncle had just hiked a quarter-mile to the base of Roaring Brook Falls. They had their backs to a "rock slide" as they stood on a small pile of rocks and faced the falls, Whitelaw said.

The rock struck the boy in the back and crushed him against a downed tree, Whitelaw said. Forest rangers and Keene Valley's rescue squad performed CPR on the boy for about 45 minutes. Whitelaw then pronounced the boy dead.

The boy's uncle had cuts to his face, hands and legs, and was treated at the scene. Although his injuries were minor, Whitelaw said the uncle "is in really rough shape emotionally. He is extremely distraught."

The boy, whose name has not been released, was from Greenwich in Washington County, Whitelaw said. The Essex County Coroner's Office and New York State Police are investigating the death. The boy's body was taken to the Adirondack Medical Center in Saranac Lake, where an autopsy will be completed Monday.

"I have (responded to) people falling off cliffs and all sorts of mishaps and medical events, but this is the first one like this," Whitelaw said.

"Anytime you're venturing into the wilderness, you have to use a little bit more caution," he said, "but they couldn't have foreseen what was going to happen."

Whitelaw said the boy's death has affected everyone who responded Sunday.

"As serene and beautiful as it seems," he said, "things can change in an instant."