Police said those arrested had been attacked in the first brawl, The Arizona Republic reported.
Youths looking for a high school senior from Surprise, Ariz., were confronted by 20 to 30 students at the Delta Kappa Epsilon fraternity house near the Arizona State University campus in Tempe, police said. A fight broke out in which one student received a head injury and the visitors fled.
Six people drove back to the fraternity house about 4 a.m. with bats and two guns, police said. Another student received a head injury that was not considered life threatening and three others were treated and released at a hospital.
A patrol officer witnessed the six alleged attackers leaving the scene and pursued them in a high-speed chase. They fled the vehicle when ordered to stop. Four were arrested Sunday morning and a fifth suspect was arrested Sunday night.
Police said they expected more arrests.
The student injured in the first fight was taken to the hospital by people at the party. While he was expected to survive, police said he was flown to another hospital for treatment.