In a major reversal, the superintendents of three large public school systems in Virginia and Maryland are calling for an all-virtual start to the fall semester, scrapping earlier plans to offer a mix of in-person and distance learning.

The superintendents of Fairfax County Public Schools and Loudoun County Public Schools, both in Northern Virginia, argued for an online-only start in meetings with their school boards Tuesday. The superintendent of Montgomery County Public Schools in Maryland announced the switch in an email late Tuesday afternoon to parents, students and staffers.

All three districts are among the largest and most highly regarded public school systems in the Washington area. They are all defying intense pressure from the Trump administration, which has urged schools nationwide to reopen their doors five days a week come fall.

In explaining his decision, Fairfax County Schools Superintendent Scott Brabrand said the United States has failed to contain the novel coronavirus.

“The covid-19 pandemic looks much different than it did even three weeks ago,” Brabrand told board members during the meeting. “Now we are experiencing a surge of covid-19 across the country, and it will impact us here in Fairfax County. The numbers do not lie.”

The Fairfax County School Board debated the superintendent’s recommendation late into the night Tuesday, in a heated meeting that lasted more than seven hours and at times devolved into a shouting match. Close to 9 p.m., the board took an informal poll at the superintendent’s request, and a majority — nine of 12 members — said they supported the all-virtual option. This consensus agreement, although not a formal vote, allows Brabrand to move forward with planning.

In Loudoun, Schools Superintendent Eric Williams advocated online-only schooling late Tuesday evening in part by citing a national increase in coronavirus cases. Near 1 a.m., after hours of discussion, the school board voted 7-2 to endorse the switch to online education.

In Montgomery County, Schools Superintendent Jack Smith will bring a detailed plan for all-virtual learning before the Board of Education for a vote on Aug. 6. In his email Tuesday, he cited recommendations from county Health Officer Travis Gayles, who recently said school should not reopen for in-person classes.

“Given this updated guidance, the safest choice for our district is to remain in a virtual-only instructional model through the first semester,” Smith wrote. “We all want what’s best for students. This decision is incredibly difficult.”

The three announcements, which tumbled out rapid-fire one after the other, left thousands reeling throughout both states. Many residents of Virginia and Maryland — including some members of the Fairfax County School Board — said they felt blindsided by the last-minute recommendations, which came weeks before school is slated to start.

The switches also came days after Fairfax, which enrolls 189,000, and Loudoun, which enrolls 83,000, had formally asked parents to choose between two enrollment options for the fall, an all-virtual plan or a hybrid one. That choice revealed a split: A clear majority of Fairfax parents, 60 percent, chose in-person learning, while a slight majority of Loudoun parents, roughly 51 percent, did. Those who did not respond were counted as selecting in-person learning.

Now, these mothers and fathers must swiftly craft new plans.

“This is NOT the way to lead,” Fairfax parent Amina Basic wrote in an email. “You don’t LET them think they have a choice then you take that choice away.”

In Montgomery County, which enrolls more than 166,000, the plan for hybrid learning had looked slightly different. Until Tuesday, the school system was considering opening the school year with distance learning but, in a matter of weeks, offering families the choice of a hybrid model that would blend on-campus learning with remote instruction.

In recent days, though, dissent had intensified. Teachers and parents — by the thousands — had called, messaged, emailed and posted on social media about the proposal. Some had supported a return to school buildings, but a majority did not, citing safety, officials with the school system said.

Teachers in particular responded with frustration last week as union leaders presented details of what the hybrid approach could involve. In recent days, Montgomery teachers had sent hundreds of emails calling for remote learning for the fall semester — and similar scenes had played out in Fairfax and Loudoun. Surveys in both districts showed teacher support for the online-only option: 52 percent of Fairfax educators indicated a preference for such teaching, and 46 percent of Loudoun teachers.

In part citing these surveys, the superintendents in both Fairfax and Loudoun said in-person schooling would be impractical this fall because too few teachers indicated they would be willing to step back in the classroom. In Fairfax, roughly 10 percent of teachers requested health exemptions under the Americans With Disabilities Act, Brabrand said, and requests for leaves of absence doubled from last year. In Loudoun, Williams said, so many teachers asked for child-care-related leave, requested leaves or resigned from their posts — saying they do not feel confident in the planned safety precautions — that it would be impossible to offer in-person instruction for every student whose family requested it.

Fairfax’s Brabrand asked a handful of principals, whom he had invited to the videoconference, to explain their personnel predicaments.

“The bottom line is, without additional staffing — actually having significantly more teachers — we cannot make this work,” said Amy Goodloe, principal of Rocky Run Middle School.

Educator reactions such as these, coupled with concerns about rising coronavirus infection rates, have already persuaded large school systems throughout the country to opt for an online-only start to next school year. Although the science around reopening is inconclusive and it remains unclear how easily children spread the virus to adults, school systems in Los Angeles, San Diego and Atlanta have already picked the all-virtual path.

Until Tuesday, Fairfax, Loudoun and Montgomery were three of the final holdouts in the Washington area. Over the past two weeks, almost every major district in the region had announced plans to begin fall classes online, ignoring speeches and tweets from President Trump, who has insisted schools must reopen.

Fairfax has come under special heat from the Trump administration, twice drawing censure from Education Secretary Betsy DeVos over not reopening. DeVos had insisted the Virginia school system was failing students — and criticism continued from conservative quarters after news broke of Fairfax’s about-face Tuesday. Fox News host Laura Ingraham wrote on Twitter that it marked “horrific news for families.”

During Fairfax’s virtual board meeting Tuesday, some lamented what they saw as the politicization of a decision that should have focused solely on the health of students and staff members.

“The pandemic experience,” said Fairfax County Health Director Gloria Addo-Ayensu, “has been very political.”

But most of the meeting was devoted to a heated debate over the risks and merits of reopening. School Board members grilled the superintendent and health officials present on the call over whether virus infection rates in Fairfax County justified a decision to delay reopening.

Benjamin Schwartz, the Fairfax County Health Department’s director of epidemiology and population health, noted that cases are surging in the United States and in Virginia as a whole. But he acknowledged that case rates in Fairfax County have not risen in over a month — although he predicted that infection rates in Fairfax are likely to spike four to six weeks from now, given that the county is just embarking on some reopening measures.

“The metrics as they exist today do not suggest an increasing problem in Fairfax County,” Schwartz said. “But [the decision] has to be based on what can be extrapolated in the modeling.”

That four- to six-week delayed spike would come just as schools are supposed to reopen, Brabrand said. In defending against criticism from some board members, the superintendent also repeatedly referenced Montgomery County: That county has a smaller number of cases than Fairfax, he said, and health officials still advised against reopening.

School officials spent hours quibbling over whether case rates should be the most important metric or whether other data should prevail when calculating the risks and rewards of reopening. Late in the evening, the board formally voted to ask the superintendent to develop clear public health metrics for reopening, stipulating that he must present them to board members by mid-August. Some also mentioned the cost to families who will now struggle to find child care, to balance working from home with managing small children or to keep jobs that cannot be completed from home.

But even as health officials cited slideshow presentations stuffed with numbers and explanations, the conversation almost always returned to one thing — how much we don’t know.

“The challenge we’re faced with is the unknown,” Addo-Ayensu said. “There are answers that we don’t have, because we’ve never seen this before.”

School Board student representative Nathan Onibudo said he wondered whether Fairfax will really be able to reopen only once a coronavirus vaccine appears. He said no one knows when or whether that will happen.

Board member Melanie K. Melen (Hunter Mill) asked how long families can last with online-only education.

“Virtual learning is essentially telling everyone to stay home,” she said. “Is that the plan for years? What’s the breaking point?”