Mayor Bill de Blasio said in an interview Sunday that the coronavirus pandemic has "only just begun" and that he fears that the "worst is yet to come."

The interview on CNN came as the state released updated case numbers: more than 15,100 coronavirus cases have been confirmed in New York, with more than 9,000 of those in New York City. More than 60 fatalities have been confirmed in the city.

"April is going to be a lot worse than March, and I fear May could be worse than April. I think that's the honest truth," de Blasio said. "I think we're about 10 days away now from seeing widespread shortages of really fundamental supplies – ventilators, surgical masks, the things that absolutely are necessary to keep a hospital system running."

The mayor echoed calls made by Gov. Andrew Cuomo on Sunday for the federal government to invoke powers to mandate private companies to manufacture much-needed medical supplies.

"It's true, companies are trying their damnedest to step up, but the president of the United States is not stepping up," de Blasio said on CNN. "He, right now, this minute, could mobilize the United States military because if they don't get involved, anything that's produced around this country won't get to where the need is greatest. The only logistical capacity that could actually save us in real time is the military. Their medical personnel are sitting on the bench. They don't want to sit on the bench. But that's what's happening because the president hasn't given the order. And if you don't order companies to maximize production of ventilators, surgical masks, all of the things that are desperately needed, and you don't organize that and prioritize where it's going to go, it won't happen in time – and we just have to be clear about this. This isn't something where everyone just makes up their own mind and you hope the stuff arrives in time."

Earlier Sunday, FEMA chief Peter Gaynor said in an interview on CNN that the federal government hasn't had to invoke the Defense Production Act yet because companies around the country have been stepping up voluntarily. Gaynor noted that the president can use "that lever" at any time.