An employee at Sing Sing Correctional Facility in Ossining, New York, has tested positive for the coronavirus, NBC News has confirmed. Two other people, neither outwardly showing symptoms, have been tested, and those results are pending, according to the state Corrections Department.

Prisons and jails across the country are grappling with how to prevent coronavirus outbreaks in packed correctional settings. The Los Angeles County sheriff announced Monday that the inmate population had been reduced by more than 600 people and that the number of arrests per day had decreased from about 300 to 60.

The New York Corrections Department said it is following health protocols and guidelines and is working to trace the contacts that the person who tested positive may have had. Sing Sing is a maximum-security prison housing about 1,300 inmates.

Jermaine Archer is serving 22 years to life in Sing Sing for second-degree murder. In a phone conversation Sunday, he cited fears of a possible outbreak and said he hadn't been informed of any contingency plans should someone test positive.

Full coverage of the coronavirus outbreak

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

"People are really worried. I haven't seen people," Archer said. "I was still in Sing Sing for 9/11, and I remember that, and people have the same looks on their faces when I walk by.

"It's more like concern and worry, like helplessness," Archer added. "What can we do with someone else's mercy? The biggest concern, again, is what is the contingency plan?"

The concept of social distancing has been repeated as a key health guideline to reduce the spread of the virus that causes the disease COVID-19. Archer says that remains difficult in a prison facility.

"It's impossible, absolutely impossible, because right now there's no visitors, so we have to use the phones," Archer said. "You've got to wipe it down between every person. Guys have to use the kiosk machine to send out emails. Guys have to touch the trays in the mess halls to eat. Guys have to touch their cell bars. Guys have to hand their ID cards to staff."

Bianca Tylek, executive director of Worth Rises, a nonprofit advocacy organization focused on prison labor, told NBC News that she was particularly concerned about the elderly population in prisons and whether adequate accommodations would be made.

"This is going to be absolutely catastrophic inside prisons, particularly with the U.S. having an aging population," Tylek said. "The circumstances for folks who are incarcerated are remarkably grave."

The Corrections Department banned all visitations at New York correctional facilities until April 11 "to prevent additional spread of infectious viral transmission of COVID-19 in both correctional facilities and the community writ large."

The department said that in place of visitations, it was offering inmates a free phone call each week, five free stamps and two free secure messages to help keep communication lines open.

"I have pretty grave concerns," said Dr. Homer Venters, a physician who is former chief medical officer of New York City Correctional Health Services, adding that the "high level of filth and squalor" in prisons can contribute. "Patients will get sick in these places and will not be adequately monitored."

"Jails and prisons may actually drive this epidemic curve up," he added. "These are places that can serve as reservoirs or accelerators of an outbreak."