Kings County on Sunday reported 376 new cases of COVID-19, one of the largest jumps in the number of cases in any county in Central California.
Health officials said most of those cases - 373 in total - were from state correctional facilities.
The county also reported its fifth death since the outbreak began.
This brings the total number of coronavirus cases in Kings County since the outbreak began to 1,122. Of those patients, 304 have recovered and five have died.
Avenal State Prison is the source of a large number of those cases.
COVID-19 outbreak at Avenal State Prison, 25 inmates and 7 staff members infected
According to the California Department of Corrections and Rehabilitation's website, 596 inmates have tested positive for the virus. Of those, 592 remain in custody, while four have been released.
The prison saw a large jump from 273 active cases on Thursday, May 28 to 593 active cases on Friday, May 29. Health officials have said recent spikes in the prison are due in part to increased testing.
Tracking Central California COVID-19 cases
Corcoran State Prison, also located in Kings county, has one inmate suffering from COVID-19.
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COVID-19 outbreak spreads in Avenal State Prison, over 300 more inmates test positive since Thursday
This brings the total number of coronavirus cases in Kings County since the outbreak began to 1,122