After a crush of travel cancellations in March, WanderJaunt, a short-term home-rental startup in San Francisco, laid off 56 of its 240 employees at the end of the month.

Demand for services from Wonderschool, a startup that helps people find day care and preschool providers, dropped by half, leading it to cut most of its 60-person staff.

And at ClassPass, which offers a membership program for fitness classes, more than 95% of revenue evaporated in just 10 days as studios and gyms around the world shut down. To survive, the startup slashed spending, froze hiring and rushed to build a video-streaming service for virtual workouts.

“This is the great unwinding,” said Martin Pichinson, head of Sherwood Partners, a Santa Clara advisory firm that restructures failed startups. In recent weeks, he said, his firm has fielded a “firestorm” of calls — a volume three or four times the highest he had ever seen.

Startups have always been risky, designed to grow fast or die, but the coronavirus pandemic is turbocharging Silicon Valley’s natural selection and causing a shakeup so sudden it has defied comparison. In just a few weeks, more than 50 startups have cut or furloughed roughly 6,000 employees, according to a tally by the New York Times. Plans for initial public offerings are on hold. And funding is drying up for many young tech companies.

The fallout is hitting the highest-profile startups as well as the smaller ones trying to disrupt them. Airbnb, the San Francisco home-rental startup valued at $31 billion, has stopped hiring and has suspended $800 million of marketing. Bird, an electric scooter startup, laid off 30% of its staff last month; while Everlane, an apparel company, cut or furloughed hundreds of workers.

Real estate startups Knotel and Convene have laid off or furloughed half their workers. Hiring site ZipRecruiter cut around 40% of its staff. OneWeb, a satellite startup that had raised $3 billion in venture funding from investors including SoftBank, the Japanese conglomerate, filed for bankruptcy and is seeking a buyer. And travel startups — Vacasa, Sonder, Inspirato, Zeus Living and TripActions, among others — have been some of the hardest hit.

Daniel Zhao, a senior economist at Glassdoor, a workplace review and job listings site, said the situation facing startups now is worse than in downturns like the dot-com bust in the early 2000s and the financial crisis of 2008.

“The coronavirus outbreak is economically akin to a major hurricane occurring in every state around the country for weeks on end,” he said.

In March, job listings at the 30 most valuable startups in the United States dropped 19%, or an average of 21 jobs each, according to Thinknum Alternative Data, a research company. Startup funding in the first three months of 2020 was also on a pace for its second-steepest quarterly decline in 10 years, said CB Insights, which tracks startups.

Startups in some areas — telemedicine, food delivery, online learning, remote work, gaming — are thriving amid the quarantines. And there were signs that things were shaky even before the coronavirus brought wide swaths of the U.S. economy to a halt.

But the pain is now deeper and most likely just beginning, especially as investors, already bruised by a string of disappointing IPOs last year, become even more cautious. On March 5, Sequoia Capital, a top venture capital firm in Menlo Park, issued a warning to startups, calling COVID-19 “the black swan of 2020.”

For startup workers, the past few weeks have been sobering. Many had bought into the tech industry’s change-the-world ideals, had few boundaries between their work and personal lives and hoped for big payouts if their startups went public.

Now they are being laid off over video calls.

At Bird, the Santa Monica scooter startup that had once been valued at as much as $2.5 billion, hundreds of employees were invited to a video conference call with just an hour’s notice. On the call, the voice of an unidentified executive explained that their jobs had been eliminated. A slide outlined the terms: a month of severance pay, three months of medical benefits and one year to exercise their stock options.

The end was equally abrupt for Nik Buenning, 40, a data scientist at Panoramic, a marketing software startup in Los Angeles. He was just settling into his work-from-home setup March 23 when a companywide email said to expect a call from human resources.

Right away, he said, “people started sending Slack messages like, ‘I’m out.’ ‘I’m out.’ ‘I’m out.’” An hour later, he was out, too.

Buenning signed up for Upstream, a new networking app that unveiled itself earlier than planned to cater to tech workers affected by coronavirus layoffs. Sites like Silver Lining are also helping people connect with companies that are still hiring.

Michael Chen, 30, is CEO of WanderJaunt. The 4-year-old company, which had raised $27 million in funding, has slashed its prices. And it has switched its focus from vacation travelers to those displaced by the virus, like stranded college students, people seeking a separate workspace or medical workers isolating themselves from family.

At Sonder, a travel startup in San Francisco that laid off 282 people and furloughed 135 of its 1,254 workers, the speed of decision-making has increased from a few days to a matter of hours.

Sonder has raised $345 million in funding and was valued at $1.1 billion. CEO Francis Davidson said his investors had advised him to cut fast and deep.

“People that are looking for a really coddled environment should not be in startup land,” he said.

Many venture capital firms are flush with cash from record-breaking hauls in recent years. But they may not decide to use the money to keep struggling startups alive.

Alpha Bridge Ventures of San Francisco said it is too small to pour more money into its startup investments. The firm has made a promise to the founders it has backed: If their companies fail because of the coronavirus, it will give them $25,000 for their next company.

In lieu of lavish events, venture firms are now dispensing advice in blog posts, on Twitter and at virtual panels over Zoom. At a March startups event, Alexis Ohanian of Initialized Capital in San Francisco, encouraged founders to adapt to the new reality.

“If what you’re doing now is just not a viable solution in this new world and in a different economy,” he said, “then find something that is.”

Erin Griffith is a New York Times writer.