The Los Angeles County Sheriff's Department said the call was received shortly before 9 p.m.
Deputies placed the area on lockdown and evacuated students and spectators north toward Imperial Highway while they searched for a suspect.
Authorities said they had not found any evidence of a shooting as of Friday night.
Video from the scene showed at least one woman being taken away on a stretcher. The nature of her injuries was not immediately clear.
Further details were not immediately released.