NEW YORK (Reuters) - New York State will ban gatherings of more than 500 people beginning on Friday at 5 p.m. (2100 GMT) , to slow the spread of the new coronavirus, Governor Andrew Cuomo said on Thursday.

FILE PHOTO: New York Governor Andrew Cuomo delivers remarks at a news conference regarding the first confirmed case of coronavirus in New York State in Manhattan borough of New York City, New York, U.S., March 2, 2020. REUTERS/Andrew Kelly

Establishments that can fit 500 people or fewer must halve their capacity, Cuomo said.

Broadway theaters in Manhattan must start observing the rules on Thursday night, Cuomo told reporters at a news conference in Albany. Soon after the announcement, the Broadway League trade association announced it would immediately suspend all shows, a major driver of New York City’s tourism industry, until April 12.

Cuomo declined to say how long the ban would last. He said it would be evaluated daily.

“This is about science, this is about data,” Cuomo said, describing these as extraordinary measures for a state that includes the most populous U.S. city. “Let the science, let the data make the decisions.”

New York City Mayor Bill de Blasio was to brief reporters later in the day.

As of Thursday afternoon, 328 people in New York state were confirmed to have contracted the new coronavirus, which causes a sometimes deadly respiratory disease called COVID-19. A minority of those people have been hospitalized, and so far no deaths have been reported in New York.

Cuomo said hospitals, nursing homes, mass transit and certain other facilities will be exempt from the new rule, which state officials said only applied to “congregant spaces.” An office building that fits more than 500 people would not be subject to the rule, but a single open-plan office space that fits 500 people would.

In the neighboring state of New Jersey, Governor Phil Murphy recommended canceling all gatherings of more than 250 people.

On Wednesday night, Cuomo announced that New York City’s centuries-old St. Patrick’s Day, due to take place on March 17, would be postponed.

Cuomo expressed frustration with slow progress in ramping up testing capacity, although he declined to attribute blame. The state has authorized 28 labs to carry out diagnostic tests for suspected COVID-19 patients who meet certain criteria, Cuomo said. The World Health Organization this week called the outbreak a pandemic.

“We are way behind in testing,” Cuomo said. “There’ll be plenty of time to do a retrospective. We need to increase testing as quickly as possible and get the volume as high as possible. The more people you test, the more people you can isolate.”

The state has also contracted with a national laboratory, which Cuomo did not name, to do automated testing, which speeds up the process. Once the U.S. Food and Drug Administration approves that step, the state could run 5,000 tests a day, Cuomo said.