The prison declared an emergency and requested multiple ambulances after the fights broke out at several prison housing units around 7 p.m.
The ambulances transported three inmates and six staff members to area trauma centers for treatment.
The injuries were not considered life-threatening.
The incident happened at the United States Penitentiary Victorville, which is a high-security facility within the larger Federal Correctional Complex.
The USP currently houses 1,206 male inmates.