COSBY, Tenn (WATE) — The National Transportation Safety Board is leading the investigation into the cause of a fatal helicopter crash on Wednesday near Cosby, about 15 miles northeast of Gatlinburg.

One person died in the crash, according to Sevier County Sheriff’s Office. The helicopter came down near the Sevier-Cocke County line on Apple Tree Lane, just off U.S. Highway 321.

The flight path of a helicopter that crashed in Cosby along the Sevier-Cocke County line. Source: FlightAware.com

A second person on board the flight was seriously injured, according to the Federal Aviation Administration, who said in an incident notification on Thursday that the Robinson R-44 helicopter received “substantial” damage after it “crashed east of the GKT airport in the foothills of the mountains for unknown reasons.”

Flight data shows the private helicopter took off at 2:13 p.m. from Gatlinburg Pigeon Forge Airport in Sevierville and was in the air for about 8 minutes before dropping off of radar in the mountains.

Tom and Barb Reau told WATE 6 they saw the helicopter fall from the sky near their home.

“We had our window open, I was sitting over in the chair, and we heard the struggling engine” Barb Reau said. “And then all of a sudden he looked at me and said ‘oh my gosh its going down.'”

“I could see the white of the helicopter … and he was going nose first into the trees,” Tom said. “I followed him down until I couldn’t see him anymore. I didn’t hear an explosion or anything.”

Steve Sherman, a gas station attendant at a convenience store less than a mile away, said he heard a “boom” and went to investigate. Next thing he knew, first responders were rushing by to get to the scene.

This is a developing story. Download the WATE 6 News app for updates sent to your phone.

A Sevier County Sheriff’s Office vehicle is parked to block the road where a helicopter crashed on Dec. 29, 2021.

EDITOR’S NOTE: This story has been updated to reflect current information.