A 26-year-old man from Princeton Junction was assaulted at an event at Terrace Club around 2 a.m. Sunday, Borough Police said.
The victim was hospitalized with at least nine slash wounds, treated and released later that day, police said Monday. No suspects have been identified.
The victim and witnesses described the assailants as a group of 12 to 15 black men between the ages of 18 and 22, according to a police report. The assailants wore black T-shirts with a silver design on the front, and a few displayed black or blue bandanas around their wrists.
The incident occurred at an alcohol-free fundraising event sponsored by the campus chapter of Delta Sigma Theta, a predominantly black sorority, Terrace President Becky Gidel '06 said in an email.
"Among those invited to the party were members of the sorority and members of their brother fraternity," Gidel said.
Fraternities and sororities on campus are not officially recognized by the University.
Neither the suspects nor the victim appear to be connected with the University, Borough Police Lieutenant Nicholas Sutter said. The description also does not match any of the known gangs in the area, he said.
According to the police report, the victim was dancing at the event when he asked an individual to "stop bumping into him." The victim said the man then gestured to several others, who dragged him into a hallway and attacked him for several minutes.
Though the victim did not realize it at the time, he was slashed more than nine times with what appeared to be a box cutter or straight razor, the report said.
After escaping the scene, he called a friend to drive him to the hospital. On the way, they flagged down a Borough officer, who alerted the station.
Police from the Borough, Public Safety and Princeton Township responded to the call to assist with crowd control.
"By the time we got there, the crowd was essentially gone," Public Safety Deputy Director Charles Davall said in an interview.

The incident appears to be isolated and unrelated to the University, Davall said, but Public Safety will release a University statement if an ongoing threat is anticipated.
Gidel emphasized that the club is committed to maintaining a safe environment.
"This is the only event held at Terrace that allows non-PUID students to enter the club," she said. "I have never known a violent incident to have occurred at Terrace, and we owe much of that to our dedicated security team. Our atmosphere is, has always been, and always will be, to be a welcoming and safe club for all Princeton students."