Millions hole up at home as jobs are threatened nationwide.

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 81 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, Fla., 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.