The student was assaulted at student housing near campus around 1 a.m. Saturday, campus police said. She knew her attacker, but authorities would not elaborate if they were friends or acquaintances.
SDSU police have a person of interest in mind who is not a SDSU student.
In September, three sexual assaults were reported, involving acquaintances. Those victims knew or hung out with their attackers earlier in the day, according to investigators.
Some students were upset to hear about the latest sexual assault and told Fox5 the university was not doing enough to prevent the attacks.
"Horrible things continue to happen to these innocent students," a SDSU student said. "Something clearly isn't being done to protect them and I'm not spending thousands of dollars to go to a school I can't feel safe at, or that my friends can't feel safe at."
SDSU officials said last month, they offered education programs and activities to help students make good decisions in social situations, as these recent sexual assaults involved acquaintances and not strangers.
The university's freshman orientation on "Sexual Assault Awareness and Prevention" has also been expanded from 5 to 30 minutes in length.