According to the Ventura County Fire Department, the plane involved was a Hawker Hunter jet trainer.
The jet had taken off from Naval Base Ventura County with another aircraft and crashed as it was returning at about 12:15 p.m. near the base. The crash was about two miles from the runway in the middle of a farm field.
The civilian pilot was declared dead at the scene. Authorities say there was no one else aboard.
The cause of the crash has not yet been determined. Debris at the site of the crash covered an area about the size of a football field.