Homeless experts and some federal housing officials are sounding the alarm that the patchwork of government efforts to address the coronavirus outbreak risks leaving out one group of acutely vulnerable people: the homeless.

Housing advocates say they fear an outbreak could occur in large homeless encampments where thousands of people live on the street and lack the ability to self-quarantine, receive medical attention or access cleaning facilities.

Shelters across the country are grappling with the enormous challenge of increasing capacity to get more people off the streets and increasing space between the beds within their facilities to reduce the risk of spread, according to housing experts and shelter operators.

Homeless outreach workers say they are struggling to get critical information about the virus to homeless people who are without the Internet and, in many cases, unaware of the dangers posed by the coronavirus. At the same time, several large shelters have told federal officials that the volunteers they depend on are staying home at a worrisome rate and cannot be replaced, according to one senior Trump administration official who spoke on the condition of anonymity to discuss internal planning.

The White House and Department of Housing and Urban Development have to this point not moved to deploy emergency funding to help the homeless or housing shelters. The bipartisan agreement that was approved by the House late Friday also did not include any measures aimed at the homeless, despite concerns raised by advocacy groups to congressional lawmakers. The measures announced by President Trump on Friday likewise did not include any specific provision for the homeless.

Exacerbating the danger is that the coronavirus has begun rippling through the U.S. economy, causing layoffs across a number of industries and putting low-wage workers at risk of being evicted. Only a handful of cities have approved or are considering temporary moratoriums on evictions during the pandemic, leading to fears of a potential increase in the homeless population.

“Congress is about to pass an emergency spending bill that entirely neglects the urgent needs of people experiencing homelessness,” said Diane Yentel, president of the National Low Income Housing Coalition. “Providing resources to protect against an outbreak of coronavirus among people who are homeless is not only a moral imperative, it’s an urgent public health necessity.”

The senior administration official said work has begun on asking Congress for money in the next aid package, including emergency funding for shelters to pay their rent or leases. Two congressional aides said Democratic lawmakers were also working on such a request, but the timeline for such legislation is uncertain. The officials spoke on the condition of anonymity because they were not authorized to speak on the record.

“Funding to protect homeless Americans is very much part of the discussions between the administration and Congress as we work toward a final agreement,” HUD spokesman Matt Schuck said in a statement.

The Trump administration has also provided shelters and other housing agencies with information from the CDC about social distancing and creating appropriate cleaning stations to prevent spread. HUD said it is working to provide “maximum flexibility” to allow communities to use their HUD grant money to help health-care and homeless providers stem the outbreak. HUD Secretary Ben Carson also said this week that the Federal Emergency Management Agency would probably bear responsibility for handling a response to the potentially massive increase in need for shelters.

The congressional aid package includes measures that may indirectly help the homeless, including new money for unemployment insurance and food stamps. Some cities have also ramped up their response to protect the homeless, implementing eviction moratoriums; handing out hand sanitizer and other cleaning supplies to the homeless; and, in a few cities, looking at leasing hotel spaces for use by the homeless.

But interviews with more than a half-dozen housing activists and shelter operators show shelters are already struggling with constraints on their resources as they grow increasingly alarmed about the coronavirus. In San Jose, numerous shelters are depleted of masks, hand sanitizers and bleach, said Jennifer Loving, chief executive officer of Destination: Home, a nonprofit organization in Santa Clara County. They are struggling to figure out how they would quarantine people in crowded shelters should someone with symptoms arrive needing help.

“We need resources to be able to isolate vulnerable homeless folks,” Loving said. “We are in a crisis and need federal resources immediately.”

In Fremont, Calif., shelters have enough supplies to last only 10 days and have been unsuccessfully asking local governments to help erect cleaning stations outside the shelter doors, according to Louis Chicoine, chief executive officer of Abode Services, one of the largest homeless shelters in the Bay Area. Chicoine said local authorities are overwhelmed by requests for help. Many of the shelter’s volunteers are old and staying home to avoid exposure or have children and have to stay home because of school and child-care closures.

“We have stockpiled some supplies, but nothing like what we think we are going to need,” Chicoine said. “The wave is going to hit in such a way that people living in the streets will be dramatically impacted.”

So far, only one homeless person nationwide has tested positive for the virus, the senior administration official said. But homeless people are particularly likely to have additional health conditions that could exacerbate the impact of the illness, advocates say, and one study from last year found the homeless to be far more likely to have asthma and other pulmonary conditions.

In Kansas City and Seattle, public libraries are closing because of the coronavirus, depriving the local homeless population of a warm, dry place where they can wash their hands, use a clean bathroom, charge their phones, connect to the Internet and rest during the day. Some homeless shelters said they were wrestling with the degree to which they should be focused during the outbreak on getting people off the streets.

“There’s a terrible tension here: You want people inside, out of their tents and encampments, so they can get critical services and potentially better access to health care,” said Philip Mangano, president and CEO of the American Round Table to Abolish Homelessness. “But with the coronavirus, is that the healthier option for them? People outside may be able to accomplish social distancing and self-quarantining, rather than being cloistered together.”

Some advocates have tried taking their concerns directly to HUD. Andy Bales, who runs Union Rescue Mission in Los Angeles’s Skid Row, asked Carson and HUD official Richard Youngblood about the federal government’s preparedness at a meeting at the agency Tuesday, attended by Rescue Mission officials from across the country. Bales asked whether the Trump administration would activate FEMA to build emergency facilities to mitigate the devastation the coronavirus could cause to homeless populations. The HUD officials listened to Bales but did not commit to executing his request.

Bales set up a quarantine area at a gym that can accommodate about 175 people, while he suspects thousands of homeless people in the city will be at risk.

In Seattle, homeless outreach workers are adopting “practical” emergency solutions such as passing out homemade hand sanitizers along with other emergency supplies to help people “shelter in place” while government officials build modular “isolation units” to quarantine people who have fallen ill, said Alison Eisinger, executive director of the Seattle/King County Coalition on Homelessness. Officials anticipate the need for several thousand such units. Eisinger said the National Guard should be mobilized to help support the response.

“This pandemic is so unprecedented that it needs a federal-level response,” said Margot Kushel, a doctor and director of the University of California at San Francisco’s Center for Vulnerable Populations, who focuses on homelessness in older adults. “We need resources to allow state and local health departments and homeless service organizations to execute their plans immediately.”

Yasmeen Abutaleb contributed to this report.