Seven armed public safety officers and seven more unarmed community service officers sought to corral an unruly crowd of about 150 people milling about on a chilly Halloween night, waiting to enter a party at the University of Southern California’s grand ballroom.

Before officers established order, multiple shots rang out in the air, sending dozens in every direction, away from the area near the iconic Moreton fig tree on the east side of the Ronald Tutor Campus Center, the student union building and just south of Tommy Trojan. Officers rushed in searching for the shooter and weapon.

“People were running in every direction—even the wounded,” said David Carlisle, captain of USC’s Department of Public Safety. “Thirteen minutes later the suspects were arrested.”

The “Freak or Greek” party — which advertisements for the event say was organized by USC’s Black Student Assembly and an event company called LA Hype — attracted 400 attendees, public safety officials have said. USC has not provided documentation related to the party. A Black Student Assembly official declined to comment Thursday afternoon.

(MORE: USC Halloween Party Planner Critical Of Campus Police)

According to the event invitation, the costumed celebrations were open to anyone 18 and older or with a valid college ID. The invite also advised attendees to “pregame” before the party, something that a sign inside the ballroom reiterated.

“University policy requires that any student parties on campus be open only to guests with student IDs from USC or another university, “ USC President C.L. Max Nikias said in a statement Thursday morning.

A handful of students have already responded to this policy by putting a petition on change.org asking for an amendment to the current rules.

USC’s social event policy dictates that all formally organized parties that go on past 10 p.m., include alcohol or play loud music (live or recorded) must occur on weekends.

Per the university’s student guidebook: “Of these items, the presence of alcohol is the single most important aspect of events which are considered unacceptable on evenings preceding days on which classes are scheduled.”

The Halloween event would have been in violation of these standards because the party took place on a Wednesday night, there were classes Thursday, the venue played loud music and festivities continued on past 10 p.m.—but it was exempted from the rules.

(MORE: USC Shooting: Officials Acknowledge Gaps In Monitoring Halloween Party)

After numerous calls—and in-person requests—for comment to university officials, Vice President for Student Affairs Michael L. Jackson sent the media an email saying the following:

“…The event in question was approved as an exception to the university’s date and time requirements because no alcohol was to be served and to allow the student group to hold an event on Halloween.”

This evening, the USC Widney Society holds its Inaugural Gala, bringing dozens of millionaire donors on to campus.  USC’s unarmed security ambassadors are out in full force guarding the area.

Read the full policy here. 

UPDATE: Vice President for Student Affairs Michael L. Jackson confirmed via email that the student organization working in conjunction with LA Hype is the Black Student Assembly.

Reach Senior News Editor Sarah Parvini here.