Santa Rita Jail in Dublin reported its first case of an inmate testing positive for COVID-19 on Saturday.

The inmate is in stable condition in the jail’s medical unit and is under continual monitoring by staff in a negative pressure room, according to a news release from Alameda County.

An investigation is underway to identify, monitor and test staff and inmates who came into contact with the infected inmate, who had been living in a two-person cell. Inmates in the infected person’s immediate vicinity are being quarantined, and the area is being professionally cleaned and sanitized, according to the release.

Jails and prisons around the country have been reporting cases of COVID-19, and this latest case comes as some activists are calling for jails to release inmates to protect them from the virus. Experts worry an outbreak could spread quickly through the state’s overcrowded jail and prison system.

The Alameda County Sheriff’s Office has stopped booking certain offenders —  jailing only those suspected of committing serious and violent crimes such as child abuse, sexual offenses and human trafficking — and has reduced its inmate population by almost 600 people so far.

In Santa Clara County, 11 sheriff’s office staff, including eight jail deputies, have tested positive for COVID-19. One inmate also tested positive but has since recovered and been moved back to his normal housing unit.

Elsewhere in the region, a Contra Costa County jail deputy, an Alameda County jail nurse, and at least four employees with the San Francisco Sheriff’s Office also have tested positive for the virus.