LONDON — From France to Russia, from Britain to the Czech Republic, European leaders are confronting a surge in coronavirus cases that is rapidly filling hospital beds, driving up death tolls and raising the grim prospect of further lockdowns in countries already traumatized by the pandemic.

The continent, which once compared favorably to the United States in its handling of the pandemic, is being engulfed by a second wave of infection. With an average of more than 100,000 new infections per day over the past week, Europe now accounts for about one-third of new cases reported worldwide.

In the most vivid sign of the deteriorating situation, President Emmanuel Macron of France on Wednesday imposed a curfew of 9 p.m. to 6 a.m. in the Paris region and eight other metropolitan areas, beginning on Saturday. “The virus is everywhere in France,” he told the French public, as he declared a state of emergency.

The resurgence has prompted officials to close bars and clubs in Prague and Liverpool, and to make face masks mandatory in public indoor spaces in Amsterdam. In Russia, which reported its largest daily increase in infections on Wednesday, President Vladimir V. Putin sought refuge from the torrent of bad news by announcing that his government had approved a second vaccine.

Chancellor Angela Merkel of Germany better captured the anxious mood when she said on Tuesday, “I am watching with great concern the renewed increase in infection numbers in almost every part of Europe.” Ms. Merkel added, “We mustn’t throw away what we achieved via restrictions over the past months.”

To some extent, Europe’s setback is hardly a surprise. Public health experts have long warned that the virus could roar back when the days grew colder, driving people indoors, where the risk of transmission is far greater.

In several European countries, lockdowns were lifted abruptly, sowing complacency among people who felt they could return to their normal lives. In the face of intense political pressures, European leaders have been reluctant to impose new, economically damaging lockdowns, often opting for the lightest possible measures.

For Germany and a handful of its neighbors, this second wave is particularly demoralizing because they had navigated the first wave relatively well. In late June, revelers in Prague celebrated the end of the outbreak with a dinner party stretching across the Charles Bridge. Spain and Italy, which were hard hit in March and April, threw open their doors to vacationers in July and August.

Now, with these countries experiencing an alarming spread of the virus, the carefree days of summer are a distant memory.

On Wednesday, Ms. Merkel and Mr. Macron announced a raft of nationwide restrictions in their countries, ranging from the closing of bars and restaurants to the mandatory use of masks. The curfews in Paris and other French cities, including Lyon, Toulouse and Marseille, will last at least four weeks.

“We haven’t lost control,” Mr. Macron insisted. “We are in a situation that is worrying that justifies being neither inactive nor panicked.”

Germany reported 5,132 new infections on Tuesday, up from 2,639 a week earlier; France reported 120,000 new cases over the past seven days, one of the highest rates in the world.