President Donald Trump invoked emergency authority to marshal industry to fight the coronavirus, as the economic fallout from the pandemic mounted Wednesday with major U.S. auto manufacturers saying they are shutting down their North American factories.

The announcements came hours before China said the former virus epicenter of Wuhan and its surrounding province had reported no new cases, a dramatic development in the city overwhelmed by thousands of new patients each day when the outbreak was peaking there last month.

On a day of head-spinning developments:

— Stocks tumbled again on Wall Street on fears of a prolonged recession, falling so fast they triggered another automatic trading halt. The Dow Jones Industrial Average shed more than 1,300 points, or over 6%, and has now lost nearly all of the big gains it had posted since Trump's inauguration. Oil dropped below $21 per barrel for the first time since 2002.

— More borders slammed shut across Europe and North America, with the U.S. and Canada closing their boundaries to all but essential travel and Trump saying he plans to assert extraordinary powers to immediately turn back to Mexico anyone who crosses over the southern border illegally.

— The White House pressed Congress to swiftly pass a potentially $1 trillion rescue package to prop up the economy and speed relief checks to Americans in a matter of weeks.

Calling himself a “wartime president,” Trump invoked the Defense Production Act of 1950 to steer industrial output and overcome shortages of face masks, ventilators and other supplies as hospitals brace for an expected onslaught of cases.

The Korean War-era law gives the president extraordinary authority to compel industries to expand production and turn out vital materials. It was most recently used after the 2017 Puerto Rico hurricane to speed up contracts for food and other necessities.

"It's a war," Trump said, likening the coronavirus fight to measures taken during World War II and warning of national sacrifices ahead.

China's health ministry ministry said Thursday that all 34 of its new cases were in people arriving from abroad. Eight new deaths were reported, all in Wuhan, where the first cases of COVID-19 were reported in December and which remains under the quarantine control measures imposed weeks ago to stop its spread.

The virus has since infected more than 217,000 people worldwide and killed over 8,700, mostly in China, Italy and Iran. The United Nations warned that the crisis could lead to the loss of nearly 25 million jobs around the world.

Though China still has the largest number of cases, most of its patients have recovered. China even sent medical supplies to hard-hit France, returning a favor done by the French weeks ago.

But in a grim illustration of the pandemic's shift, deaths in Italy were nearing China's toll. Italy had more than 2,900 dead after a record one-day total of 475; China's overall toll was around 3,200. Iran has also been hit hard, with more than 1,100 deaths.

More than 83,000 people overall have recovered from the virus, which causes only mild or moderate symptoms such as fever and cough in most cases. Severe illness is more likely in the elderly and those with existing health problems.

Around the globe, governments took increasingly drastic measures to fight the epidemic and the threat of a recession, in some cases using emergency powers.

California's governor warned that martial law could be imposed. The mayor of New York said the city's 8.6 million residents should be prepared for a lockdown. The U.S. Census Bureau suspended field operations for two weeks, soon after it began its once-a-decade count of American people.

Czech authorities used emergency powers to raid a warehouse and seize hundreds of thousands of face masks. And Hong Kong widened the use of electronic wristbands that monitor people under self-quarantine.

Theodore Peck, who owns a Brooklyn coffee shop and bakery, was in quarantine at home as a precaution when New York City this week ordered all bars and restaurants to close except for takeout. He had to shut down his business and lay off all his workers.

“My life's work is being ... you know, destroyed, like picked over,” he said.

Peck lamented that he didn't even get the chance to say goodbye to 22 of his employees.

With a growing number of Americans thrown out of work by the near-shutdown of much of the U.S. economy, Trump also said the Housing and Urban Development Department will suspend foreclosures and evictions from public housing.

The Trump administration's plan for issuing relief checks to Americans calls for the payment of $500 billion in two installments over the next two months. The amounts have yet to be decided but would be based on income and family size.

Seattle-area tattoo artist Travis Tolin lost his only source of income when the shop he works for shut down. He took to Facebook to ask friends for moral support.

“We’re all going to be struggling for a bit so all I ask is that you support small businesses if you’re fortunate enough to still be working, buy prints, music, jewelry, anything they have available,” Tolin said. “We will all get through this!!”

Ford, General Motors and Fiat Chrysler, along with Honda and Toyota, said they will shut all of their factories in the U.S., Canada and Mexico. The closing of Detroit's Big Three alone will idle about 150,000 workers, who are likely to receive supplemental pay in addition to unemployment benefits.

At GM’s pickup truck assembly plant in Flint, Michigan, workers have been fearful since the virus surfaced in the U.S., said Tommy Wolikow, who has two young daughters.

“That’s the thing that I was scared the most about, being the one to bring it home to them,” he said.

The U.S. reported more than 7,700 coronavirus cases and at least 138 deaths, about half of them in Washington state, where dozens of residents from a suburban Seattle nursing home have died.

Rep. Mario Diaz-Balart of Florida is the first known member of Congress to test positive for the virus. Other members of Congress have self-quarantined, but none have reported positive test results.

Miami Mayor Francis Suarez, who last week announced he tested positive, is sharing his experience in a daily YouTube diary and on Twitteras he runs the city from home isolation. His wife and children are staying with relatives.

“The longer I live with COVID-19, the more I understand just how crucial social distancing is,” Suarez wrote.

Scientists have no doubt the true number of people infected is higher than reported because of the possibility that many mild cases have gone unrecognized or unrecorded, and because of the lag in large-scale testing in the U.S.

In the first breakdown of its kind in the U.S., the Centers for Disease Control and Prevention said that the nation's coronavirus deaths so far mirror what has been reported in other countries, with about 4 out of 5 fatalities occurring in people 65 and older, and no deaths in children.

Scientists in China reported disappointing results from the first study completed on a potential COVID-19 treatment. A combination of two antiviral drugs used now to treat HIV did not resolve symptoms quicker than usual care in a study of 199 hospitalized, severely ill patients. The findings were reported Wednesday in the New England Journal of Medicine.

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Associated Press reporters around the world contributed to this report.

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The Associated Press receives support for health and science coverage from the Howard Hughes Medical Institute’s Department of Science Education. The AP is solely responsible for all content.

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Follow AP coverage of the virus outbreak at https://apnews.com/VirusOutbreak and https://apnews.com/UnderstandingtheOutbreak

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The headline has been corrected to say 200,000 virus cases, not deaths.