NORCO, Calif. (AP) — A one-of-its-kind World War II-era flying wing aircraft crashed and burst into flames in the exercise yard of a Southern California prison on Monday, killing the pilot, authorities said.

The Northrop N-9M crashed around midday "under unknown circumstance" at the California Rehabilitation Center in Norco shortly after takeoff from nearby Chino Airport, said Federal Aviation Administration spokesman Allen Kenitzer.

The pilot was the only person on board the historic aircraft, Kenitzer said.

Riverside County sheriff’s officials said the crash was fatal. Nobody on the ground was seriously hurt, although one inmate received scratches, according to the state Department of Corrections and Rehabilitation.

Television news footage showed debris from the yellow aircraft spread across a scorched patch of empty yard at the prison about 50 miles east of downtown Los Angeles.

Several people in the area reported hearing a loud noise and then seeing smoke rising into the air.

Susan Fracol, who watched the plane go down, told reporters it was "heartbreaking" to witness.

The N-9M was the last remaining of four flying models developed in the 1940s by aviation pioneer Jack Northrop as a predecessor to what he hoped would be a full-size heavy bomber. That program was canceled, but many years later the flying wing concept resurfaced as what became the B-2 stealth bomber.

Northrop was fascinated by the flying-wing concept and believed that such a pure airfoil surface would have the most efficient lifting capabilities. He formed a small company of his own, the Avion Corp. in Burbank, Calif., and in 1929, his first Flying Wing made a successful maiden flight from Burbank Airport.

During the Great Depression of the 1930s, Northrop temporarily shelved his flying-wing dream to create some solid moneymakers. Then in 1939, Northrop broke away from United to form a completely independent firm, Northrop Aircraft Inc., and relocated to Hawthorne, Calif., where he resumed his flying-wing experiments in 1940. His next attempt, the N-1M, was the genuine article, dispensing with the boom-mounted tailplanes. The N-1M originally was powered by twin 65-hp Lycoming engines driving pusher propellers, but it underwent several changes in power plant and wingtip configuration in the course of more than 200 flights.

The historic N-1M was preserved and is now on display at the National Air and Space Museum.

Northrop continued to experiment with flying wings like the N-9M and JB-1 during World War II.

After several other experimental projects, Northrop developed the XB-35 and YB-35 experimental heavy bomber aircraft for the United States Army Air Forces during and shortly after World War II. Only prototype and pre-production aircraft were built.

The single-seat N-9M that crashed was returned to flying condition in 1994. FAA records show the owner as the Planes of Fame aircraft museum in Chino, which was preparing for an air show next month. The museum confirmed on its website that a pilot died and the plane was lost.

The FAA and the National Transportation Safety Board will investigate the crash, Kenitzer said.

The medium security prison houses about 2,700 inmates.

Jon Guttman of Aviation History Magazine, a sister publication, contributed to this report.