11/01/2012 05:13 am ET Updated Jan 01, 2013

USC Halloween Shooting Wounds Several People, Two People Detained (UPDATE)

Two people have been detained by police in connection to shots that rang out at a Halloween party on the USC campus Wednesday night. The campus remained on lockdown at around 1:30 a.m. Thursday as police continued to investigate but it was lifted shortly afterward.

At least four people were wounded in the shooting, one of them critically, the Los Angeles Times reports.

A tweet sent out from USC indicates that neither the suspect nor the victims are students, staff or faculty at the school.

Assistant Chief John Thomas of the USC Department of Public Safety told KNBC that the violence stemmed from a dispute between two non-students, reports the Associated Press.

The shooting took place at the Tutor Campus Center, where a concert venue was hosting a "Ghosts 'N Stuff" Halloween party, reports university paper Neon Tommy.

Neon Tommy contributor Matt Hamilton was near the center, along with up to 200 partygoers, when shots rang out at around 11:30 p.m. or 11:45 p.m. Wednesday. He noted that police response was swift:

Police came very quickly. There were already USC campus police at the event because they were patrolling the event. I think that’s partly why there was such a quick response. There were already many officers on the scene already. While crouching, I saw more police come to the scene. Within minutes, LAPD. I saw fire trucks. Helicopter overhead. Ambulance.

Immediately after the shooting, the campus was put on lockdown as police searched for the gunman. Below is a tweeted picture of the school 30 minutes after the attack: