USC Department of Public Safety Captain David Carlisle said an argument between two men who had no relation to the school led to one of the men pulling out a gun and shooting the other.
That victim was struck in the torso three or four times and was rushed to a hospital in critical condition.
Three bystanders were taken to the hospital with non-life threatening injuries.The two men were arrested by USC security officers who followed them as they fled toward a parking garage.
A gun was also recovered on the scene.
The campus went on lockdown after the shooting, but has since resumed normal activity.
Jordan Shepherd | Elite.