LONDON — Prime Minister Boris Johnson announced a second national lockdown on Saturday as his scientific advisers warned that surging coronavirus infections could overwhelm British hospitals in six weeks.

As Britain passed the milestone of 1 million coronavirus cases, Johnson spoke at a gloomy news conference, saying he had hoped to avoid another sweeping lockdown but was confronted with stark data showing the virus was spreading rapidly.

The restrictions in England come amid a surge in cases across Europe that has forced closures, curfews and other measures in France, Spain, Germany and elsewhere.

“We will get through this, but we must act now to contain this autumn surge,” said Johnson, who contracted covid-19, the disease caused by the coronavirus, in March and spent three days in intensive care in a London hospital, where he said medical workers gave him “liters and liters of oxygen.”

Looking ahead, he acknowledged that “Christmas is going to be different this year, maybe very different.”

Starting on Thursday, and until Dec. 2, all nonessential shops, pubs, cafes, restaurants and gyms in England have been ordered to close. Grocery stores, child-care facilities, schools, colleges and universities will remain open.

Those who can work from home were urged to do so, and Johnson stressed that those older than 60 should not go to work if possible.

The restrictions were announced for England. The other parts of the United Kingdom — Wales, Scotland and Northern Ireland — will pursue their own versions of lockdowns, some of which have already begun.

The prime minister’s message undercut hopes that Britain could continue with his government’s policy of targeted and tiered regional restrictions.

“We’ve got to be humble in the face of nature,” said Johnson, who conceded that the virus was ripping through society “faster than our reasonable worst-case scenarios.”

The prime minister said that if nothing more was done, England would experience several thousand deaths a day, far worse than at the peak in April.

He asked people to imagine hospitals in the National Health Service overwhelmed in a matter of weeks, with doctors and nurses having to ration even oxygen and forced to decide “who would live and who would die.”

The virus has already cost Britain billions in lost earnings. Johnson on Saturday said his government would extend through November its popular furlough program, which covers 80 percent of the wages of low-to-middle-income workers who are temporarily laid off.

The new measures will be subjected to a vote Wednesday in Parliament, where Johnson’s Conservative Party holds an 80-seat majority.

The new lockdown comes as Britain reported 326 deaths related to covid-19 on Saturday, bringing the toll to 46,555, according to government tracking. Another 21,915 new infections were recorded, bringing the total number of cases to more than 1 million.

European governments are struggling to contain a steep second wave of autumn infections after the relative success of strict lockdown restrictions in the spring.

“We in Europe are all surprised by the propagation of the virus,” French President Emmanuel Macron said in a televised address to the nation this past week.

Portugal announced a lockdown affecting 70 percent of the country staring Nov. 4. Also Saturday, Austrian Chancellor Sebastian Kurz said his country would implement “hard measures” beginning Tuesday, with a nationwide lockdown to include nightly curfews from 8 p.m. until 6 a.m., according to the Local in Austria.

“People will still be allowed to go to work, to provide help, and to stretch their legs, but it is a ban on visiting other people during these hours,” Kurz said, blaming private visits among family and friends as the main driver behind the surge in infections.

“In Austria we’ve seen an exponential increase in cases and in the last few weeks, and an almost explosive increase in the past seven days,” Kurz said.