More than 800 inmates and 25 staff at the Lompoc Federal Corrections Complex have now tested positive for COVID-19.
The latest update from the Bureau of Prisons website on Friday shows 792 inmates and 11 staff at the Federal Correctional Institution (FCI) have tested positive, meaning about 68 percent of the inmate population at the low-security facility.
Another 31 inmates and 14 staff at the medium-security United States Penitentiary (USP) also have confirmed cases.
The increase in numbers comes after the prison began testing all of the inmates in the low-security unit of the complex this week.
Local health officials say while many of the inmates have tested positive, a majority of them have mild symptoms or no symptoms at all. They add that they are still seeing some cases among prison staff, but not a "huge increase."
Officials say two inmates at the prison complex have died as a result of COVID-19.
Oliver Boling, 66, died on April 17 and Jimmie Lee Houston, 75, died on May 6. Prison officials said both had long-term, pre-existing medical conditions and died at outside hospitals.
The prison was set to open a newly constructed "hospital care unit" on prison grounds Wednesday. It will be used to treat ill inmates who would normally require outside hospitalization.
Prison officials have said, in addition to other social distancing measures to prevent spread of the virus, inmates have been restricted from using telephone and email stations. They are encouraging friends and family members of inmates to instead correspond by sending letters through the mail.
Patriotic-colored signs of support for the BOP could be seen along the prison complex fencing Friday.
The total case count at the prison varies between county health officials and the BOP due to when test results are received.