PORTLAND, Ore. (AP) - A prominent California race horse breeder was one of two men killed in a small plane crash in a remote area of Oregon, authorities said Thursday.

Witnesses told authorities they saw the twin-engine plane break up on its way to the ground Wednesday and that it was destroyed following impact near the historic Riddle Ranch on Steens Mountain, about 80 miles south of Burns.

Frank ``Scoop'' Vessels, 58, a past president of the American Quarter Horse Association, and Sam Cannell died when the Aero Commander 500-B piloted by Vessels crashed on its way to Montana from Redding, Calif., said Harney County Sheriff Dave Glerup.

The plane was registered to Vessels, the owner of Vessels Stallion Farm near San Diego. He owned First Down Dash, the most prolific sire of quarter-horse earners, and was inducted into the American Quarter Horse Hall of Fame earlier this year.

Cannell, 73, of Anderson, Calif., was an architect, as well as a horse owner and breeder. He was a partner with Vessels on the horse Little Bit of Baja, said Mark Williams, a quarter-horse breeder who owns River Hill Ranch in Redding.

Vessels Stallion Farm said Thursday that the two friends were going on a fishing trip when the crash occurred.

The cause of the crash has not been determined. The National Transportation Safety Board and the Federal Aviation Administration were investigating.

Vessels is the grandson of Frank Vessels Sr., who founded the Los Alamitos Race Course. Vessels said in 2003, after receiving the John W. Galbreath Award, that his grandfather gave him the nickname ``Scoop'' because he used to hang around the horse stalls as a child.