LOS ANGELES -- The University of Southern California in Los Angeles has suspended a fraternity following reports of an alleged sexual assault and "possible drug-facilitated sexual assaults" at its house, school officials said.
"The university has received a report of sexual assault at the Sigma Nu fraternity house," the school said in an alert posted on its Department of Public Safety website Wednesday. "The university also has received reports of drugs being placed into drinks during a party at the same fraternity house, leading to possible drug-facilitated sexual assaults."
The university reported the information to the Los Angeles Police Department, according to the alert, which encouraged anyone with information "relevant to the crimes" to contact the school's Department of Public Safety and police.
An LAPD spokesperson told ABC News Thursday the department is aware of four alleged victims, none of whom have reached out to police yet. The LAPD opened an investigation on Thursday, the department said.
The alleged assaults occurred on Sept. 25 at a fraternity party and involved unlawful administration of a controlled substance, possibly through an alcoholic beverage, police said. There is no suspect information at this time.
According to a USC Department of Public Safety log, from Sept. 27 to Oct. 20, six different incidents of drugging were reported at the Sigma Nu house. One of those drugging incidents also involved a sexual assault. Another drugging incident was reported during the same timeframe, but the location was undisclosed.
The Sigma Nu fraternity has been placed on interim suspension and is barred from hosting parties, social gatherings or any other activities at its house, the school said.
The national Sigma Nu Fraternity said in a statement Thursday that it is "concerned by these serious allegations" and aims to work with USC on investigating them.
"The Fraternity will determine its further actions based upon the investigation," the statement said. "Sigma Nu Fraternity remains committed to responding appropriately to all matters of confirmed misconduct."
Several students Thursday evening gathered outside the Sigma Nu house in support of the alleged victims.
Some students there said the issue has been ongoing for several weeks.
"I mean the fact that this happened over multiple weeks over and over, and the guys were confident enough that they could do this multiple weeks in a row to multiple women - that they would not get in trouble, and that it would just be fine, says everything about how safe men feel hurting women," student Sophie Beitel told our sister station KABC.
By Friday morning, the frat house was covered in graffiti and protest signs condemning sexual assault and what they believe is a toxic part of Greek life culture.
"It's a message to people that this matters and I just hope that people come and they read the signs and see the frustration and anger," said USC sophomore Claire Smerdon. "I hope it means something."
"There definitely needs to be more of a conversation, more action needs to be taken," said student Shelbi Woodard. "I think this should definitely only be the beginning."
KABC contributed to this report.