New York City health officials have identified a total of 11 neighborhoods experiencing an alarming rise in coronavirus cases, up from 10 on the previous day.

All told, the city is monitoring what they are calling four clusters located in Southern Brooklyn, Williamsburg, Central Queens and Far Rockaway. In an update on Thursday evening, the Department of Health released a revised list of neighborhoods and ZIP codes. Two neighborhoods on the list appear to be new: Brighton Beach in Brooklyn and Rego Park in Queens. The Queens neighborhood of Fresh Meadows/Hillcrest, which had been added on Wednesday, was removed.

The 14-day test positivities in the 11 neighborhoods range from 3.2% for Rego Park in Queens to nearly 7.2% for Brooklyn's Gravesend. Many of the neighborhoods are home to large numbers of Orthodox residents, and health officials have targeted outreach to that community by speaking with religious leaders as well as disseminating and broadcasting information in Yiddish.

Overall, mask compliance is up in many of the neighborhoods, although some residents in Williamsburg this week said they received anonymous robocalls urging them not to get tested. The public health focus on Orthodox residents has threatened to deepen the wedge between the city and some community members who say the attention spurs anti-Semitism.

Speaking to WNYC's Brian Lehrer on Friday, Mayor Bill de Blasio sought to downplay the clusters by saying that they are not reflective of the spread of the virus in other parts of the city.

"If you look at the vast majority of the city right now most neighborhoods are at 1 % or less," de Blasio said.

The citywide seven-day average positivity is 1.6%. With the 11 neighborhoods removed, it becomes 1.2%.

"It's just exactly where we have been, and very very favorable," the mayor described.

In addition to the 11 neighborhoods, health officials have said they are monitoring seven additional neighborhoods that are also seeing a concerning increase in cases.

Dr. Denis Nash, an epidemiologist at CUNY, classified the clusters as outbreaks and pointed out that all New York City neighborhoods are linked by mass transit.

"Having outbreaks now [in those neighborhoods] could absolutely affect what is happening in the rest of the city if we don’t get it under control," he said.

The cases in the 11 neighborhoods account for about 30% of new cases citywide over the past two weeks, while representing less than 9% of the city’s overall population, health officials said.

Public health experts have increasingly described a second wave in New York City as all but inevitable. They have cited the reopenings of schools and resumption of indoor dining as well as the shift to colder weather, which makes the virus more transmissible and forces more people indoors.

New cases in the city are now tallying around 400 a day, up from less than 300 two weeks ago. The mayor has said that if cases reach 500 new daily cases, he would consider pulling back on the city's reopening.

De Blasio, however, said that he did see that as a scenario "any time soon." But he warned limited shutdowns in the 11 neighborhoods was a possibility if cases continue to rise.

As part of its updated alert on Thursday, the Department of Health said that it had issued a new Commissioner’s Order which grants city agencies the power to issue closure orders to businesses for repeat non-compliance with public health regulations related to COVID-19.

The city has been regularly inspecting yeshivas and businesses in the 11 neighborhoods. Since Tuesday, the city has closed five yeshivas, and issued 23 summons to individual businesses. No businesses have yet been ordered to close.

During a telephone call with reporters, Governor Andrew Cuomo on Friday threatened to fine New York City under a state ordinance that allows them to fine local governments up to $10,000 a day for failing to enforce public health rules. He said that state health officials would be on the ground in certain neighborhoods.

Although he has not mentioned de Blasio by name, Cuomo has criticized the city for failing to crack down on those violating religious gathering, social distancing and face mask rules.

"Compliance is enforcement. Compliance is not public education," he said, a veiled reference to the city's public awareness campaign in the affected neighborhoods. "People know what the rules are, they’ve heard it everyday."

In response to the governor's remarks, Mitch Schwartz, a spokesperson for the mayor said, “New York City has inspected nearly 1000 businesses in just the last three days. We’re enforcing guidelines with the speed and rigor this crisis demands – not because we fear fines, but because we know our measures will help combat this crisis. Public health and safety drives the day in this city.”

Friday at sundown marks the beginning of the Jewish holiday of Sukkot, a celebration of the fall harvest that for some involves eating and sleeping for eight days in a sukkah or tent outside. Because of the outdoor nature of the festival, Cuomo said he was not expecting to see a rise in cases directly as a result from it.