NORAD said the intercept of the Piper 28 aircraft occurred at around 9:45 a.m. PDT. A pair of F-16s escorted the small plane to El Monte Airport, where the pilot was detained by local police and later handed over to the Secret Service.
It all turned out to be an apparent misunderstanding. Investigators believe the pilot simply made a mistake. There was no threat to the president.
The Associated Press contributed to this report.