It is unknown how many people may have been on board. The Los Angeles County Fire Department confirmed two people are dead, one male and one female.
Rescuers are still conducting a search and rescue for any possible victims on a hillside near Cal Poly Pomona.
The crash also sparked a small grass fire.
Capt. Frank Reynoso of the Los Angeles County fire department said the original report of the crash came from hikers in the area.
Reynoso said it appears the plane hit near some warehouses and homes, but crashed into vacant land.
City News Service contributed to this story.
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