The day before state authorities announced plans to restrict inmate movement and revoke visits and other privileges, three inmates were killed in attacks at three different prisons.

High-security prisons across California have tightly restricted movement, calls and visits while officials probe a surge in violence this year. The restrictions started Saturday and affect the top-security sections of nearly a dozen lockups including the California Correctional Institution,

The California State Prison, Sacramento is among facilities that are being placed on modified movement after a surge in violence, correctional officers said.