A single-engine Lancair IV crashed near State Route 76 around 9 a.m., according to the San Diego Sheriff's Department and Ian Gregor of the Federal Aviation Administration.
CHP Officer Tony Polizzi said one person in the car died and three others were taken to the hospital. He says two people in the small plane also were transported for treatment.
The conditions of the injured were not immediately known.
The FAA and National Transportation Safety Board will investigate the crash.
The Associated Press contributed to this report