New York City Mayor Bill de Blasio warned on Thursday that social distancing restrictions may need to be tightened and extended until June to contain and prevent the coronavirus outbreak from resurging, saying it's going to be a "long, tough" April. "Unfortunately, restrictions may have to go up, meaning if things really get worse, we might have to tighten up further," de Blasio said at a press conference. "It's not what I envision today. It's not what any of us want. But the truth is the truth. I don't think anyone watching out there wants to be told pretty lies." De Blasio said the last thing New York can afford is to see a resurgence in the disease now that there's been some evidence that the spread is starting to slow. It may not be June until the city starts loosening some of its restrictions, he said. "April, we're going to have to fight this fight the way we are now into May, that could be a lot of May in fact. I would love it if some change could happen in May. But it may not be until June," de Blasio said.

Mayor Bill de Blasio speaks as the Navy Hospital Ship USNS Comfort arrives in Manhattan's Pier 90 to help relieve the strain on local hospitals with its 1,000 beds and 1,200 personnel during the Coronavirus (COVID-19) pandemic in New York City. Ron Adar | Barcroft Media | Getty Images

New York City is grappling with the worst COVID-19 outbreak in the country with more than 81,800 confirmed cases as of Thursday morning — more than half of all cases across the state and almost as many as China, according to data compiled by Johns Hopkins University. De Blasio outlined three phases of the outbreak that show where the nation's largest city needs to be before officials will even consider reopening it. Right now, there is "widespread transmission" of COVID-19 where the city is unable to keep track of all the cases or trace where they originated, de Blasio said. "You're seeing constantly new cases. ... We cannot trace the origins of individual cases back to their original source," he said, adding that the city has to ration testing right now. The city needs to get to "low-level" transmission, which is when they are able to trace cases to their source and test more people, before officials will consider loosening some social distancing restrictions, according to a chart presented at the press conference. The third phase, "no transmission," is when new infections are primarily coming from outside New York City.