Searchers were working early on Thursday to retrieve the bodies of four people who died in a private plane crash in a mountainous area of north Georgia, authorities said.

The bodies and the wreckage of the Beech Bonanza V-35A were found on Rich Mountain late Wednesday, said Paige Joyner, spokeswoman for the Civil Air Patrol, a volunteer organization leading the search.

"They had to rappel into (the crash site) from a helicopter, that's how difficult the terrain was," she told Reuters.

The plane left the Gilmer County Airport at 10:30 a.m. Monday on a sightseeing trip and never returned.

Officials from the National Transportation Safety Board are also expected to be in Gilmer County, about 90 miles north of Atlanta, to investigate the cause of the crash, said Joyner.