Reports of domestic violence increased in March in many cities around the country as the coronavirus pandemic spread, according to law enforcement officials — raising concerns about families’ safety as they isolate at home.

Of the 22 law enforcement agencies across the United States that responded to NBC News’ request for data on domestic violence calls, 18 departments said they had seen a rise in March. Houston police received about 300 more domestic violence calls in March than they did in February, a roughly 20 percent increase. Charlotte-Mecklenburg, North Carolina, police fielded 517 additional calls about domestic violence in March compared to the same month last year, an 18 percent jump, while Phoenix police received nearly 200 more calls, an increase of nearly 6 percent.

“The financial stress alone creates a ticking time bomb for some families with a history of domestic violence,” said Steve Mueller, sheriff of Cherokee County, South Carolina, which saw a 35 percent increase in cases in March compared to February. “Unfortunately many of these domestic violence cases occur in front of children and often the children become victims of abuse and assault, as well.”

The rise in reports of domestic violence incidents comes as shelters for abuse victims scramble to find ways to stay open. Many regularly operate near capacity and sometimes turn to local hotels to house families when they run out of space, which gets expensive quickly. Several nonprofit shelters said they’ve canceled or postponed fundraisers because of stay-at-home orders, blowing six-figure holes in their annual budgets.

“We are contending with soaring demand in services but at the same time declining resources and financial support,” said Alejandra Y. Castillo, CEO of YWCA USA, which has dozens of shelters for abuse victims nationwide.

While the numbers from police and shelters are preliminary, they appear to support what many experts expected to happen: As city and state leaders ordered people to stay home to ward off COVID-19, the disease caused by the coronavirus, domestic abuse would become more prevalent. Victims rights advocates and police attribute the phenomenon to the stress from businesses and schools closing, leaving many people out of work and financially strained. Similar increases in domestic violence have been documented after natural disasters, such as Hurricane Harvey in 2017.

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The United States recorded its first coronavirus-related death at the end of February, and businesses began closing in mid-March when President Donald Trump declared a national emergency. Soon after, on March 16, six counties in California’s Bay Area issued one of the first major shelter-in-place orders, which was soon followed by other cities and statewide orders. That’s when many police and domestic violence service providers say they began seeing an escalation in calls.

In addition to Houston, Phoenix and Charlotte-Mecklenburg police, law enforcement in Boston; Milwaukee; Seattle; San Antonio; Salt Lake City; Utah County, Utah; Fresno County, California; Montgomery County, Texas; East Baton Rouge Parish, Louisiana; Buffalo, New York; Sparks, Nevada; Portland, Oregon; Nassau County, New York; Cherokee County, South Carolina; and Charleston, South Carolina said that domestic violence cases increased in their jurisdictions in March.

“Those domestic violence incidents are dangerous and can escalate quickly and so we have a real concern about those numbers,” said Detective Greg Wilking, of the Salt Lake City Police Department, where the weekly domestic violence cases jumped from 73 to 96 in mid-March.

Police in Cincinnati, Denver, New Orleans and New York City said their rates of domestic violence calls and arrests remained flat through March.

The National Domestic Violence Hotline’s call volume has remained average during this period — between 1,800 and 2,000 per day. During the second half of March, 1,765 hotline callers reported that their abusive partner was leveraging COVID-19 to “further isolate, coerce, or increase fear in the relationship,” according to Katie Ray-Jones, CEO of the National Domestic Violence Hotline. And she worries those numbers don’t capture the full picture.

“We are especially concerned that survivors will be unable to reach out for help due to their abusive partner monitoring their behaviors while they are in isolation,” Ray-Jones said.

As domestic violence shelters gear up for a potential increase in abuse victims seeking a place to go, many expect money to become an issue.

Twenty-one YWCA associations have told the organization’s national headquarters that they predict a drop in funding for their domestic violence and sexual assault services, and a dozen anticipate closing a program or facility for abuse victims.

Sharon Roberson, president of YWCA Nashville & Middle Tennessee, said they’re rushing to figure out what to do if one of their shelter clients shows symptoms of the coronavirus. Local hotels and colleges have already told the shelter that they won’t house sick clients, Roberson said. She considered renting RVs, but the shelter doesn’t have the funds to cover that, so now the Nashville branch is holding a set of beds empty in an isolated area within the facility for any client with COVID-19.

“We’ve had to substantially adjust the way we go about doing our business,” Roberson said, noting that calls to their crisis line increased by 55 percent in recent weeks. “We’re scrambling around to figure out how to keep people safe, with the idea we could be dealing with people who have a very contagious illness. Hospitals are very important, but we’re a version of that — we have people dealing with significant trauma and they need to have a safe space to go.”

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Donna Garske, executive director of the Center for Domestic Peace, a nonprofit shelter in San Rafael, California, said they have 21 women and about 50 children in transitional housing, apartments that the shelter helped the women find. But nearly all of those women have lost their jobs or had their work reduced because of stay-at-home orders, she said, making it more difficult for them to pay rent.

The Center for Domestic Peace is trying to secure emergency funding to help those women, Garske said, even though the shelter just had to cancel its biggest annual fundraiser.

“If we’re not out of this by the end of June, that would be a major concern,” Garske said.

If you or someone you know is experiencing domestic violence, call the National Domestic Violence Hotline at 1-800-799-SAFE (7233).