The so-called "X-files" are among more than 2,000 government documents recently digitized and available on the FBI's Vault Web site.
ABC cited one report attributed to FBI agent Guy Hottel from March 1950 about flying saucers from an Air Force investigation. The investigator told Hottel he thought the device was spotted because a powerful radar array in New Mexico had interfered with its operation.
"They were described as being circular in shape with raised centers, approximately 50 feet in diameter," Hottel wrote. "Each one was occupied by three bodies of human shape but only 3 feet tall, dressed in a metallic cloth of a very fine texture. Each body was bandaged in a manner very similar to the blackout suits used by speed flyers and test pilots."
One of the files has Roswell emblazoned across the top. It talks about a hexagonal disc suspended from a balloon cable. UFO lore long has included stories about a crash at Roswell, N.M., and a festival is held annually to celebrate it.
The Vault can be found at http://vault.fbi.gov.