Immigration and Customs Enforcement (ICE) on Tuesday revealed the first confirmed case of coronavirus among the tens of thousands of immigrants in its custody across the country.

A Mexican immigrant held in New Jersey tested positive for the virus, officials announced in a statement Tuesday afternoon. The 37-year-old immigrant is being quarantined and receiving medical treatment, the agency said.

The detainee was being held at the Bergen County Jail in Hackensack, New Jersey, which the federal government uses to detain dozens of immigrants. Officials say those who may have been exposed are being monitored for symptoms of the virus. ICE is also suspending the transfer of detainees to the northern New Jersey jail.

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Because of the confirmed coronavirus case, the Bergen County jail has been placed under a "lockdown protocol," which includes limited movement of detainees, the creation of a COVID-19 isolation unit and heightened sanitation measures and screenings of staff, county sheriff Anthony Cureton announced in a statement.

Tuesday's announcement, first reported by BuzzFeed News, comes as ICE continues to face intensifying pressure to downsize its detainee population, which stands at more than 37,000.

As the global public crisis has grown, lawyers, lawmakers, doctors and former officials have called on the agency to release immigrants with chronic health conditions, pregnant women, detainees over the age of 60 and those seeking humanitarian protections who don't pose a threat to public safety.

But the agency has yet to announce a policy of releasing certain immigrants to mitigate risk of an outbreak inside the more than 200 facilities it can use to detain people.

Last week, former ICE acting director John Sandweg told CBS News the coronavirus could "spread like wildfire" in agency facilities.

In addition to the confirmed detainee case, three staff members at ICE detention facilities have also tested positive for the coronavirus. They include an officer at the Bergen County Jail, a medical staffer at the ICE detention facility in Elizabeth, New Jersey, and a private prison company employee at a detention center in Conroe, Texas, agency officials said.