The governor’s decision to limit gatherings of more than 500 people was a blow to the theater industry, a crown jewel of New York City’s tourist trade. Last season, the industry drew 14.8 million patrons and grossed $1.8 billion.

Schools, hospitals, nursing homes and public transit will be exempt from the guidelines, which take effect at 5 p.m. Thursday for Broadway theaters and will go into effect for other venues Friday at 5 p.m., Cuomo said.

Mayor Bill de Blasio, appearing at an afternoon news conference, declared a state of emergency and stressed that the city would be dealing with the effects of the coronavirus for the long haul.

“Going to this level is not done lightly but it has reached the point where it is necessary,” he said. He cited the potential for major job losses, evictions, business closings and people running short of food.

He called the past day of developments “striking and troubling” and said that the fallout from the virus would cause a “hole in our lives.”

De Blasio also called for federal assistance, saying that “We need the federal government to move immediately with a huge stimulus program” for assistance to businesses for a period that “could easily be a half year or more.”

He said that the city could see 1,000 cases by next week.

“There are three things we want to preserve at all cost: our schools, our mass transit system, and most importantly our health care system,” he said.

In New Jersey, Gov. Philip D. Murphy recommended that all public gatherings of more than 250 people, including concerts, sporting events, and parades, be canceled across the state.

“Our front-line efforts right now must be to aggressively mitigate the potential for exposure and further spread,” Murphy said in a statement. “We are taking this step because social distancing works.”

Gov. Ned Lamont of Connecticut also issued an executive order banning all gatherings of 250 people for social and recreational activities.

As of Thursday, New York state had confirmed 328 coronavirus cases, with 112 of those added overnight, Cuomo said. One hundred and forty-eight of the cases were in Westchester County, and 95 were in New York City.

In Nassau County on Long Island, 40 people had the virus, with 10 of them hospitalized and one person in critical condition, officials said.

New Jersey announced six new positive coronavirus cases Thursday, bringing the statewide total to 29. Thirteen of those cases are concentrated in Bergen County.

Judith Persichilli, the state’s health commissioner, said hospitals are already at capacity, which is driving the recommendations on to public gatherings. The goal is to avoid a rapid spike in cases, which would overwhelm the public health system, she said.

The mayor of Jersey City, Steven Fulop, announced that the city had set a curfew of 10 p.m. for nightclubs and bars.

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New York City canceled school activities, and closed some schools for the first time.

All New York City public school assemblies, plays, after school sports and other activities will be canceled as a result of the spread of virus, de Blasio said Thursday.

The mayor has so far resisted mass school closings, citing extreme hardship for many of the city’s low-income students and their working parents.

“We want our schools to remain open, we intend for our schools to remain open,” de Blasio said.

The first two city-run public schools were closed Thursday after a parent informed the city that their child had tested positive. It is not clear when the two schools, which share a building in the South Bronx, will be reopened.

The Laboratory School of Finance and Technology, and South Bronx Preparatory: A College Board School, are both 6-12 grade schools at 360 E. 145th St. in the Bronx. The schools serve about 1,300 students combined. Nearly all of the students at both Bronx schools closed Thursday are low-income and black or Hispanic.

A student at one of the schools had a “self-confirmed” positive case of coronavirus, the mayor said in a statement.

A city official said that the child’s parent informed the city that they had tested positive for the virus, though the case is not formally logged in the state database. The city closed the schools based on the parent’s report.

The city will disinfect the school, which will be closed for at least 24 hours, and the city’s health department will investigate close contacts of the infected student who might need testing or quarantine.

“We don’t make this decision lightly, and we know the disruption and anxiety this means for students, faculty and parents,” he said.

New York City is home to the nation’s largest public school system, with 1,800 schools and 1.1 million students, and large-scale closures would inevitably be extremely disruptive.

About 75% of the city’s students are low-income, and rely on schools not only for meals, but also for in-school medical clinics, guidance counselors, laundry machines and many other services.

Students at the two Bronx schools will be able to pick up lunch at the building’s main entrance Thursday, the city said, during the same time that lunch is usually served.

Remote learning presents a challenge for city public schools, since many students do not have internet at home or live in homeless shelters.

In New Jersey, a public high school has closed to students and switched to online classes “until further notice” after a student’s sibling tested positive for coronavirus, officials said.

Red Bank Regional High School, in Little Silver, New Jersey, has about 1,200 students from Red Bank, Shrewsbury and Little Silver. It is believed to be the first public school in New Jersey to close and switch to remote learning.

The New York Archdiocese will close schools for 19,000 students.

The Archdiocese of New York will close all of its elementary schools next week, “with the possibility of a lengthier closure,” officials said in a statement Thursday.

The move affects over 19,000 students at 152 Catholic elementary schools in the archdiocese, which stretches from Staten Island north to Dutchess County but does not include Brooklyn or Queens.

The Catholic Youth Organizations and the Catholic High School Athletic Associations will also cancel all activities in the archdiocese “indefinitely,” officials said.

“We truly understand that taking this action may cause some disruption to our families, but we strongly believe that these measures taken now will have the greatest success of decreasing risk to the whole community,” the archdiocese said.

All Catholic elementary and high schools in Fairfield County, Connecticut, will also close Friday through at least March 30, the Diocese of Bridgeport said in a statement. The decision affects around 9,000 students at 29 schools.

The Met Museum, the Metropolitan Opera and others will close in response to the virus.

The Metropolitan Museum of Art said Thursday that it will temporarily close its Fifth Avenue flagship and two other locations — the Met Breuer, in midtown Manhattan and the Met Cloisters in northern Manhattan — starting Friday in response to the coronavirus outbreak.

The Frick Collection, a museum on Manhattan’s Upper East Side, announced Thursday that it was closing its galleries and library, and canceling all public events.

The Metropolitan Opera and Carnegie Hall canceled all performances and events through March 31.

The city’s other major museums have yet to announce similar plans to close, but some have already scaled back public events.

This article originally appeared in The New York Times .