LOS ANGELES — Violence that sometimes borders the University of Southern California crept onto campus when an argument outside a Halloween party escalated to a shooting that critically wounded one man and injured three other people. The episode led administrators Thursday to reassess school policies.
Neither the victims nor the two men detained were USC students, but the shooting reinforced concerns that the campus’s location near downtown Los Angeles presents risks on and off campus. The shooting comes after security was strengthened after the April slayings of two graduate students near the school.
As students returned to class Thursday after the campus was shut down for three hours, school officials said they were reviewing policies regarding visitors and events but stressed that the chances of a shooting at USC are rare.
Two men were detained and were being questioned about the shooting, which happened outside the ‘‘Freak or Greek’’ party held by the Black Student Assembly. One man was critically injured, and three bystanders were treated for minor injuries.
The men were in a line of more than 100 people waiting to get into the party when they began arguing and one man pulled a gun and opened fire, USC police said.