SALT LAKE CITY — One inmate at the Salt Lake County Jail has tested positive for COVID-19, the first announcement of a case within Utah’s jails and prison system.

Others who may have been in contact with the man, whose name was not released, were separately quarantined, Salt Lake County Sheriff Rosie Rivera said. He was being treated in a medical unit.

The announcement comes amid a new legal push to guarantee additional releases over concerns the virus could devastate the prison population. The ACLU of Utah, the Disability Law Center and the Utah Association of Criminal Defense Attorneys petitioned the Utah Supreme Court Wednesday for the release of more incarcerated Utahns.

Rivera said the county has long planned for the arrival of the new coronavirus in its jail buildings and has released roughly 1 in 3 who were held there in order to free up room in its facilities, which now house 1,654 inmates.

The sheriff announced Thursday that a deputy and a civilian employee at the jail also have the virus, but had not been there in the past five days.

“We want to assure the community who have loved ones working at or incarcerated in our facility that we are doing all we can to prevent the spread of COVID-19 and that we will continue to provide updates as information becomes available,” Rivera said. “Times of crisis are when our communities need us most and our deputies and civilian staff are answering that call.”

The man who fell ill with COVID-19 had been tested and held in an isolated cell after showing flu-like symptoms at the jail’s Oxbow location in Salt Lake City on Tuesday, she said.

While five fellow prisoners have been tested for the coronavirus, their results came back negative.

Sometime before midday Thursday, deputies wearing protective equipment transported 51 others who they suspect may have been exposed to the virus, the sheriff said in a statement. The inmates were given masks, new clothing and bedding, and an additional 94 prisoners were being evaluated by medical workers.

At the jail, more than 100 — either awaiting trial or as a penalty for violating probation — have been allowed to leave in recent weeks after prosecutors and defense attorneys in Salt Lake County came up with a list of those who are not violent and pose little public safety risk.

Judges have allowed still more to shed their jail uniforms and go home at the request of individual defense lawyers.

But the civil rights groups that filed the court petition Wednesday say that’s not enough.

They are asking the Utah Supreme Court for the release of more who are behind bars — with consideration to public safety — including:

• Defendants serving sentences with less than 180 days remaining.

• Prisoners deemed at a high risk for serious medical complications if they get the virus.

• Inmates awaiting trial.

“Extraordinary relief is an appropriate remedy in this situation where the dangerous spread of COVID-19 throughout Utah correctional facilities is nearly inevitable without immediate action,” the groups wrote in their court filing.

As of Thursday, no one being held in the Utah State Prison has tested positive for the virus, said Kaitlin Felsted, spokeswoman for the Utah Department of Corrections.

The prison and many of Utah’s jails have canceled visiting hours and volunteer work and announced plans to step up cleaning and hygiene protocol in recent weeks.