A coronavirus outbreak at San Quentin, California’s oldest prison, has infected about one-third of the prisoners, alarming health officials and sending county virus cases surging.

While San Quentin had otherwise managed to remain virus-free, officials traced the recent outbreak to a busload of 121 prisoners who were transferred to San Quentin on May 30 in an attempt to quell virus spread at California Institution for Men in Chino.

Prison officials took the incoming inmates' temperatures but did not administer COVID-19 tests, according to The New York Times.

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A California Department of Corrections and Rehabilitation (CDCR) officer wearing a protective mask stands at the front gate of San Quentin State Prison in San Quentin, California, U.S., on Tuesday, June 30, 2020. California Governor Gavin Newsom is working to release more than 3,500 prisoners who are close to finishing their sentences as Covid-19 tears through the state's correctional system, including an outbreak that has infected nearly a third of inmates at San Quentin State Prison near San Francisco. Photographer: David Paul Morris/Bloomberg via Getty Images

Since then, more than one-third of San Quentin’s 3,700 prisoners have tested positive.

"Shocking, heartbreaking are certainly the words I would use to describe it," David Sears, a physician and professor of medicine at the University of California, San Francisco, told NPR. Sears toured San Quentin on June 13 and warned state officials about the outbreak.

"It's devastating how fast this has moved through the prison," he told the outlet.

According to Dr. Matt Willis, public health officer for Marin County (where San Quentin is located), testing may have been overlooked in the rush to alleviate the virus spread in Chino.

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The New York Times reported that the prisoners shared the same showers and ate in the same dining hall as the other inmates at San Quentin. The inmates at San Quentin also sleep inches apart in a crowded dormitory, and 4-by-9 foot cells host pairs of inmates in other areas of the prison.

As of June 30, the California Department of Corrections and Rehabilitation (CDCR) reported of 2,585 incarcerated individuals statewide with active COVID-19 infections.

At a State Senate hearing on Wednesday, prison officials acknowledged their faulty decisions, with CDCR Secretary Ralph Diaz admitting they “could have done better.”

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Also, Marin County data lists a nearly 123 percent increase in cases over the last 14 days.

In a recent update, the CDCR said officials at San Quentin are installing six tents as alternative care stations to treat inmates on the grounds to allow for increased physical distancing and isolation within the prison.

The CDCR also said it will expedite qualifying inmates’ release to parole or probation under Diaz’s authority. Those with high-risk medical conditions will also be considered for expedited release.

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