The global battle reaches a new level of urgency as nations close borders.

Madrid — The global battle to contain the coronavirus reached a new level of urgency Monday, as governments locked down borders, a new wave of closures and restrictions kept more than 500 million students at home, and pleas went out to funnel masks and ventilators to places struggling with soaring caseloads.

The growing sense of crisis rocked global financial markets, particularly on Wall Street, where the Dow Jones Industrial Average plunged 12.9 percent. Investors’ fears that the outbreak will throw the global economy into a recession sent the market to its worst one-day loss since 1987.

The shifting fronts in the battle were made clear by figures showing that cases outside China — where the virus originated — surpassed those inside its borders for the first time. Spain officially became the fourth-most infected country in the world, surpassing South Korea.

With the number of cases worldwide topping 181,000, a surge of patients in Madrid’s hospitals fueled worries across Europe of what lies ahead.

“There is no easy or quick way out of this extremely difficult situation,” said Mark Rutte, the prime minister of the Netherlands, in the first televised speech by a Dutch premier since 1973.

Only China, Italy and Iran have more confirmed cases of COVID-19 than Spain, where the number of infections increased overnight by roughly 20%, to 9,191, and the number of fatalities rose to 309, according to the Spanish Health Ministry. The actual figure was presumed to be even higher, because Spain switched to a new system of reporting.

A somber Rutte told viewers that “a large part” of the Netherlands’ 17 million people are likely to contract the virus. So far, 1,413 people have tested positive and 24 have died. The government has ordered schools, restaurants and bars closed until April 6 and banned gatherings of more than 100 people.

Countries from Canada to Switzerland, Russia and Malaysia announced sharp new restrictions on the movement of people across their borders.

“We have a window of time at the moment to slow the spread of the virus,” said Ulrike Demmer, a spokeswoman for Germany’s government, which reversed its earlier insistence that border controls would not work. It imposed new limits on crossings with France, Austria, Switzerland, Denmark and Luxembourg, after cases of the virus increased by more than 1,000 over 24 hours.

With much-needed ventilators in short supply, the British government asked manufacturers, including automakers Ford and Rolls-Royce, to convert some of their assembly lines to making the life-saving equipment.