Authorities say a guard was assaulted at Anamosa State Penitentiary.
The assault occurred Sunday afternoon at the guard's post. The Iowa Corrections Department says the inmate punched the guard in the face, but other guards soon came to the aid of their colleague and subdued the prisoner.
The guard was taken to Jones Regional Medical Center in Anamosa for treatment. Department says the inmate was not injured.
The names of those involved haven't been released.