Brandon Spencer of Inglewood, Calif., was arrested on campus just after 12 a.m. Thursday, the Los Angeles Times reported Friday.
State records indicate Spence is a security guard with an active license.
Geno Hall, a former high school football star was hit several times in the shooting, which police and USC officials said began with an argument between two people not affiliated with the university.
Hall is expected to survive.
Three bystanders, none of them students, received injuries that were not considered life threatening.
USC President C.L. Max Nikias said the school would review its policies regarding visitors and events held on campus.