The attack occurred Wednesday morning. According to deputies, a man grabbed the girl, hit her in the face and ordered her to take off her pants.
The suspect fled when two other students came close.
The victim suffered a bloody nose and bruised to her face.
The suspect was last seen north of the 1300 block of East Indian Rock Road. He is described as 17 to 23 years old, white or Hispanic, between 5 foot 7 and 5 foot 9, weighing between 150 to 170 pounds and with hazel eyes.
Anyone with information is asked to call the sheriff's department at (858) 565-5200.