Millions of Americans holed up at home against the coronavirus Monday, with many of them thrown out of work until further notice, as authorities tightened the epic clampdown and the list of businesses forced to close across the U.S. extended to restaurants, bars, gyms and casinos.

With the U.S. economy shuddering to a near-halt, the Dow Jones Industrial Average plummeted nearly 3,000 points, or 13%, its biggest one-day percentage loss since the Black Monday crash of 1987.

The rapid work stoppage had Americans fretting about their jobs and their savings, threatened to overwhelm unemployment benefit programs, and heightened fears the country could plunge into a recession.

President Donald Trump acknowledged that possibility for the first time and suggested the nation may be dealing with the virus until July or August.

The number of infections in the U.S. climbed to nearly 4,500, with at least 80 deaths, two-thirds of them in hard-hit Washington state, where many residents of a suburban Seattle nursing home have been cut down by the virus. Worldwide, more than 7,100 have died.

Officials in six San Francisco Bay Area counties issued a “shelter in place” order affecting nearly 7 million people, requiring most residents to stay inside and venture out only for food, medicine or exercise for three weeks – the most drastic measure taken yet in the U.S. to curb the spread of the virus.

“I know today’s order is a radical step. It has to be. We need to act now, all of us,” said Dr. Grant Colfax, director of the San Francisco Health Department.

The shutdowns touched every corner of the country: blackjack dealers in Las Vegas, theme park workers in Orlando, Florida, restaurant and bar employees nationwide, and winery workers in California. At least eight states called on all bars and restaurants to close at least part of the day.

Tyler Baldwin, a 29-year-old bartender at the Taproom in Seattle’s Pike Place Market, one of the city’s biggest tourist attractions, shut down early “so I can go home and start figuring out unemployment, food stamps, really whatever the next step to keep myself afloat.”

In San Francisco, tour guide Manuel Gomez, 49, saw a group cancel, and Alberto Sensores, 60, cleaned windows to stay busy at an empty restaurant near heavily touristed Pier 39. Both only have savings to last them 10 to 15 days.

“I have no Plan B,” Gomez said.

Truckers hauling goods from a port in Virginia are just trying to hang on because cargo volume has dropped so much.

“It’s a struggle just to survive right now, just to put food on the table,” said Nicole Sapienza, managing member of Coastwide Marine Services in Virginia.

About 82 million people, or three-fifths of the U.S. workforce, are hourly employees. Many of them won’t get paid if they don’t work. For those in a category that includes restaurant, hotel, amusement park and casino workers, just one-third have access to paid sick leave, according to Wells Fargo.

Kevin Hassett, a former economic adviser to Trump, said on CNN that “the odds of a global recession are close to 100% right now” and predicted the U.S. could lose about 1 million jobs in April.

The economy appears to be decelerating at a much faster pace than during the 2008 financial meltdown.

“This is like an avalanche. It’s all happening at once,” said Heidi Shierholz, senior economist at the Economic Policy Institute. “And no one knows how long it’s going to last.”

On the other side of the ledger, Amazon announced it wants to add 100,000 workers to deliver packages amid a surge in online orders from people unable or unwilling to set foot in stores. And gun sales soared in many places as fear took hold.

“I’ve never seen it like this,” said Ed Turner, who owns Ed’s Public Safety in Stockbridge, Georgia. “This is self-preservation. This is panic. This is ‘I won’t be able to protect my family from the hordes and the walking dead.’”

With schools closed for tens of millions of children across the country, parents began using lesson plans that included flash cards, online learning, dog walks and creativity sessions. Many did this while juggling work conference calls, emails and memos. Others scrambled to find child care.

The shutdowns were especially devastating for the many artists and service industry workers in New York who rely on nightlife and live paycheck to paycheck in one of the most expensive cities in the world.

Ralph Anthony, a 38-year-old comic and actor in New York City, had two gigs canceled last week that cost him $1,000 – money he intended to use to pay next month’s bills.

“There’s literally no work to go around,” he said. “You’re living off your savings. You’re liquidating your investment portfolio.”

Nationwide, many restaurants were restricted to takeout or delivery only.

But “who’s going to come in for carry-outs? Not a lot of people tip on carry-outs,” waitress Danielle Livingston of Earl’s Diner in Ferndale, Michigan, lamented.

In a letter to Trump and congressional leaders, the U.S. Chamber of Commerce called for swift legislation, including a three-month cancellation of some taxes and an expansion of loans to businesses, to “mitigate the potentially devastating economic effects.”

Governors in a number of states said they are growing alarmed by the widening economic damage and effect on workers. Some announced changes to make it easier for people to collect unemployment benefits. Others accelerated programs to make loans available to small businesses.

Some analysts worry that unemployment benefit systems could be overwhelmed by people seeking aid, as happened during the height of the Great Recession over a decade ago. In fact, the website where businesses could apply for Small Business Administration disaster loans crashed Monday.

On the medical front, four healthy volunteers became the first participants in a clinical trial of an experimental vaccine against the virus, receiving shots at a research institute in Washington state. But officials cautioned that it will take a year to 18 months to fully test and approve any vaccine.

Health officials, politicians and business leaders are talking about “social distancing” and “flattening the curve,” or encouraging people to avoid others to slow the spread of the virus and keep U.S. hospitals from being overwhelmed with a sudden deluge of patients.

Most people who come down with the disease have relatively mild symptoms, but it can be deadly for some, especially the elderly and those with underlying health problems. Most people infected with the virus recover in a matter of weeks.

People forced to hunker down at home had to figure out how to entertain themselves now that nearly all social gatherings have been banned, canceled or strongly discouraged. Some planned to binge-watch TV, catch up on chores, exercise at home, do more cooking or catch up on their reading.

“I just started ‘Love in the Time of Cholera.’ It seemed appropriate,” Beverly Pfeiffer in Silver Spring, Maryland, said of the Gabriel Garcia Marquez novel.

Associated Press writers Julie Watson, Olga R. Rodriguez, Philip Marcelo, Ted Warren and Mike Schneider contributed to this report.