New York City Mayor Bill de Blasio speaks at an indoor training center at the USTA Billie Jean King United States Tennis Center which will be partially converted into temporary hospital during the outbreak of the coronavirus disease (COVID-19) in the Queens borough of New York City, New York, U.S., March 31, 2020.

"Supplies continue to come in at a very rapid rate and they go out right away to hospitals all over the city and to first responders. The speed has become remarkable," de Blasio said at a press conference Wednesday. The city estimates it will need a minimum of 2,500 to 3,000 additional ventilators over the next week, he said, adding that NYC would ship ventilators to other parts of the country as soon as they aren't needed in New York.

New York City needs to find 3.3 million N95 masks, 2.1 million surgical mask, 100,000 isolation gowns and 400 ventilators by Sunday to get the city's hospitals ready for a coming wave of coronavirus patients expected by Monday, Mayor Bill de Blasio said.

"We're going to need the masks, the N95s, gowns. Every single week we are going to need more of that," he said.

The city is also rushing to get more temporary health-care workers. State and local officials have said that doctors and nurses are all working long hours and are exhausted. "They need to see reinforcements come, they need to see some down time," de Blasio said. "They need a chance to get some downtime to finally recover."

The city is building or importing temporary hospital facilities that will add roughly 4,700 additional hospital beds by mid-April. The federal government has sent the Naval ship USNS Comfort to New York, and local and federal officials are building temporary hospital facilities at the Jacob K. Javits Convention Center, in Central Park, at the Brooklyn Cruise Terminal and elsewhere throughout the city.

New York City officials have also reserved 10,000 beds across 20 hotels to house COVID-19 patients and health-care workers so they aren't putting their families at risk.

"Many people who are working 12, 16 hours around many, many patients with COVID do not feel comfortable returning home to their spouses or their children, so we have provided hotel rooms so that they can go to a place where they feel that they can get rest without putting their families at risk."

De Blasio thanked the hotel industry: "Everyone has been working shoulder to shoulder to make this happen."

Earlier on Wednesday, Gov. Andrew Cuomo said he plans to close New York City playgrounds after warning residents for weeks to abide by new rules designed to reduce density and help curb the outbreak. Open spaces at parks in the city will remain open, he said.

New York City accounts for more than half of the coronavirus infections across the state at 47,439 people, Cuomo said.

On Tuesday, de Blasio warned that the "horizon of deepest concern" for the city is April-May after he announced part of the tennis stadium that hosts the U.S. Open will be turned into a field hospital.

CNBC's Dan Mangan contributed to this article.