The number of confirmed COVID-19 cases in New York City has reached 13,119 as of Monday night local time, according to data of the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University.

A total of 124 deaths have been reported in the city, according to the CSSE.

The largest U.S. city with a population of 8.6 million has become a new epicenter of the outbreak, taking about 30 percent of the nation's tally of 43,901.

New York City Mayor Bill de Blasio said on Monday in an interview with CNN that the situation in the city would get worse.

"It's the beginning of something that will get worse throughout April and into May and we've got to brace ourselves and we've got to change our lives and we absolutely need help from Washington," he said.

Dr. Deborah Birx, the White House's coronavirus response coordinator, said on Monday that 28 percent of coronavirus tests in the New York metropolitan area turned out positive, compared with less than 8 percent of the rest of the country.

"Clearly, the virus had been circulating there for a number of weeks to have this level of penetrance into the general community," she said at a White House briefing, adding that all New Yorkers should "absolutely social distance and self-isolate at this time."

Monday was the first day that all non-essential businesses have been closed in New York state. Streets in Manhattan were almost empty as any kind of public gathering of any scale has been banned statewide. The New York Stock Exchange temporarily closed its trading floor and shifted to all-electronic trading.

New York State Governor Andrew Cuomo, who issued the stay-at-home order last week, showed up at the Jacob K. Javits Center on Monday and announced an initial delivery of hospital supplies to the center where the Federal Emergency Management Agency (FEMA) has started to build a 1,000-bed temporary hospital.

The hospital is in addition to the four sites selected by the Army Corps of Engineers that will create temporary hospitals in southern New York state with a total capacity of around 4,000 beds.

The governor said the federal administration has deployed hundreds of thousands of N-95 masks, surgical masks, gloves, gowns and face shields to New York State, with many of which already located at the Javits Center.

The FEMA hospital is expected to open next week and there will be about 320 federal staff that come to work in it, said Cuomo.

"Luckily, Javits has plenty of space. We've been expanding Javits. This was never an anticipated use, but you do what you have to do. That's the New York way, that's the American way. And we're going to get this done," he added.

On Monday night, Mayor de Blasio said on Twitter that the city has release some prisoners in order to curb the spread of COVID-19 in jails.

At least 38 people have tested positive for the disease at the notorious Rikers Island complex and its nearby facilities by the weekend, local media reported.

The mayor tweeted that 75 people with "very limited time left on their sentences" have been released from Rikers Island, and the city is making final decisions on another 200 candidates for potential release on Monday evening.

"By Wednesday we will decide on the next 100-200 people. We want to do this smartly and safely," he added.