Bryce Segaux, an 18-year-old student at Grossmont High School, was working in the school's auto shop when he saw a small plane sputter, lose altitude and crash into another aircraft.
"There was a big old fireball," Mr Segaux said.
Mr Segaux drove over to a nearby park where he saw two bodies that
appeared to be dismembered.
Authorities closed the park after the crash and cordoned off the wreckage scene.
Some debris started a fire in the attic of a house.
Initial reports had indicated that the crash involved a small aircraft and a Robinson helicopter sometimes used for training or photography.