California began shutting down on Thursday as the nation’s most populous state enacted broad new restrictions to halt the spread of the novel coronavirus and residents attempted to adjust to the rapidly changing times.

Disneyland announced it was shutting down. Professional sports leagues suspended seasons. And more schools and college campuses across the state became ghost towns.

In a dramatic move bound to have profound social and economic impacts, Governor Gavin Newsom late Wednesday night ordered Californians to cancel or postpone gatherings of 250 or more people statewide to slow the spread of the disease through at least March. Newsom followed up Thursday morning with an executive order and made clear during a news conference that he considers the directive to be mandatory.

Newsom’s announcement followed a similar statewide call by Oregon Gov. Kate Brown and one by Washington state Gov. Jay Inslee for three Seattle-area counties hit hard by the COVID-19 outbreak.

“Each of us has extraordinary power to slow the spread of this disease,” Newsom said in a statement. “Not holding that concert or community event can have cascading effects — saving dozens of lives and preserving critical health care resources that your family may need a month from now.”

The new order — which Newsom warned would “likely be extended” beyond March — accelerated a wave of shutdowns that already had started in the Bay Area, spreading from conventions and sporting events to schools and even federal court hearings, as two judges in Oakland and San Francisco said Thursday they would suspend in-person proceedings.

Troubling signs emerged Thursday in hardest-hit Santa Clara County, where four San Jose firefighters and three Transportation Security Administration officers at Mineta San Jose International Airport had tested positive, forcing dozens of coworkers into quarantine and raising fears of further contagion. Within 24 hours, the number of known confirmed cases in the county grew by a third, bringing the total to 66, including one death. Statewide, nearly 200 people have tested positive, with half of those cases in the Bay Area.

“Several of us in city hall have been preparing for this day for weeks,” San Jose Mayor Sam Liccardo said Thursday, noting that with signs of “community spread” it was clear that officials had to “intervene in ways we never have before to protect public safety and health.”

The statewide ban on gatherings applies to all nonessential professional, social and community gatherings — such as sporting events and concerts — regardless of their sponsor.

California’s new rules do not apply to activities such as attendance at regular school classes, work, essential public transportation, airport travel or shopping at a store or mall. They also do not apply to congregate living situations, including dormitories and homeless encampments.

The directive also does not include casinos, theaters and large parks like Disneyland “because of the complexity of their unique circumstances,” Newsom said. But within hours, however, Disneyland announced it will close its iconic park and Disneyland California Adventure on Saturday through the end of March. Newsom said his administration is in discussions with theater operators and the Native Americans tribes that run California casinos on how they can comply.

Cedar Fair, which operates California’s Great America in Santa Clara, scheduled to open for the season a week from Saturday, said it plans “to welcome guests in accordance with our published schedules” but is “closely monitoring this evolving situation.” The Santa Cruz Beach Boardwalk said late Thursday that it would close starting Friday through March 27.

In addition to requiring Californians to follow the public health directives like canceling gatherings, Thursday’s executive order removes the waiting period for unemployment and disability insurance for those who lose work as a result of the outbreak. It also allows the state to commandeer hotels and hospitals to isolate and treat patients and state legislative bodies to hold public meetings via conference calls.

The order additionally calls for canceling or postponing even smaller gatherings where those attending cannot keep six feet apart from each other and limiting groups of older or unhealthier people who are more vulnerable to the disease to no more than 10.

The announcement came on a day in which the grave impact of the COVID-19 pandemic was felt across the country, with stock values diving, professional and school sports games canceling or postponing and President Donald Trump banning travel to and from Europe, as he did with China.

California — and in particular, the Bay Area — has been one of the nation’s hot zones for the respiratory disease that has sickened more than 125,000 and killed more than 4,600 worldwide. Most of the infections and deaths have been in China, but there have been major outbreaks in Italy — now under lockdown — Iran, South Korea, France, Germany and more than 1,000 cases in the U.S.

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The White House issued recommendations for Santa Clara County late Wednesday that included urging businesses to conduct health screenings for employees not working remotely. While virtually all of Silicon Valley’s big companies have already urged employees to work from home, the situation is more challenging for customer-facing businesses.

John D’Ambrosio, co-owner of Giorgio’s Italian Food & Pizzeria in San Jose and Milpitas, and Frankie, Johnnie, & Luigi Too in Mountain View, said he didn’t know if he even had a legal right to conduct such testing, and even if he did, he doesn’t have the equipment that would be needed.

“We’re not equipped,” D’Ambrosio said, adding that management is reminding its 150 employees to wash and sanitize their hands even more frequently and increase cleaning.

Newsom’s new restrictions will profoundly alter Californians lives in many ways.

For Walnut Creek resident Celine Simon, it’s been day after day of dealing with the fallout from cancellations of regular and long-anticipated events — from a weekly Girl Scout meeting to the PTA fundraiser to Tony Robbins’ four-day summit in San Jose, for which she and several friends paid $1,800 to rent an AirBnb house nearby.

“I feel like I’m discombobulated trying to figure out what to do, what’s next,” Simon said.”We’re just having to live day by day.”

Allan Zaremberg, president and chief executive officer of the California Chamber of Commerce, said that the state’s massive economy — sixth largest in the world — is so diversified that the impact of the governor’s order will be felt more in some sectors than others. But he said it would be significant, particularly in sports, entertainment, hospitality, travel and tourism.

“There are going to be ripple effects throughout the economy, that’s going to happen when these events don’t occur,” Zaremberg said. While sports leagues will likely survive the suspension of their season, he added, “there are a lot of small businesses who greatly depend on them,” such as caterers, bars, restaurants and travel services.

Staff writers Martha Ross and Ethan Baron contributed to this report.