Philadelphia Police are investigating an "acquaintance rape" that was reported on campus over the weekend.
The incident occurred inside a building near 36th Street and Locust Walk, according to Vice President for Public Safety Maureen Rush.
The victim, who may be a Penn student, knew her attacker. The case was reported to Penn Police at about 2:45 p.m. Saturday.
The Philadelphia Police Department Special Victims Unit, which is handling the case, declined to comment.
Penn Police also declined to provide further details. The Division of Public Safety issued an e-mail statement saying that it will notify the community if an incident is deemed dangerous to the public.
"Otherwise, all other instances involving sexual assault are kept confidential for the sake of the victim," the statement said.
The last known sexual assault on campus occurred last year on Jan. 21, when an 18-year-old female student reported being attacked by a college-age man near 40th and Pine streets in the alley behind Allegro Pizza. The incident reportedly occurred at about 3 a.m.
The victim in that incident said that she was walking alone after a party when she was approached by a man who offered to walk her home. Although the victim said she recognized her attacker and had seen him on campus, Philadelphia Police were not able to make any arrests.
Penn Women's Center Director Ellie Di Lapi has said that 80 to 90 percent of women who report being sexually assaulted actually know their attacker, noting that these types of victims are less likely to report the incident.
The Web site of the Rape Abuse and Incest National Network states that 67 percent of sexual assaults are committed by a non-stranger, 47 percent of attackers are friends or acquaintances of the victim, 17 percent are well-known to the victim and 3 percent are a relative of the victim.
