New York Gov. Andrew Cuomo hit back at Donald Trump on Friday after the president said he “felt” that New York, the struggling epicenter of the coronavirus, did not need the 30,000 ventilators officials have demanded.

With 519 deaths and 44,635 confirmed cases, of which 6,481 require hospitalization, the coronavirus pandemic has put New York’s medical facilities on the brink.

Cuomo has been practically begging for ventilators for days, slamming the federal government for initially sending 400 from the national stockpile when the state needed 30,000. The Trump administration later sent 4,000 more.

In an interview on Fox News on Thursday night, Trump said he doubted that states, including New York, actually needed the amount of equipment they were asking for.

“I have a feeling that a lot of the numbers that are being said in some areas are just bigger than they’re going to be. I don’t believe that you need 40,000 or 30,000 ventilators,” he said.

Then, on Friday, he wrote a series of frenzied tweets, saying General Motors, which reportedly had a plan to make ventilators that was rejected by the federal government, must immediately open a plant for production. “START MAKING VENTILATORS, NOW!!!!!! FORD, GET GOING ON VENTILATORS, FAST!!!!!!” he tweeted. (Despite his tweets, Trump had still not implemented the Defense Production Act, which forces companies to manufacture supplies, White House officials told The Daily Beast.)

In a Friday briefing at the Javits Center, which is being converted into a massive emergency hospital, Cuomo did not name-check Trump but said equipment needs were not based on “feelings.”

“Look I don’t have a crystal ball, everybody is entitled to their own opinion but I don’t operate here on opinion,” he said. “I operate on facts and on data and on numbers and on projections.”

He said experts’ projections for New York predict that the state will hit its apex for hospitalization rates in 21 days. The state is building a stockpile of resources for when that apex hits and the entire system is stressed, Cuomo said. That includes 3,000 ventilators that would be distributed to hospitals as needs arise—a fraction of the total 30,000 needed across the state.

“Those are numbers, not ‘I feel, I think, I believe, I want to believe.’ Make the decisions based on the data and the science,” he said. “I hope we don’t need 30,000 ventilators, I hope some natural weather change happens overnight and kills the virus globally. That’s what I hope. But that’s my hope, that’s my emotion, that’s my thought. The numbers say you may need 30,000.”

Health-care workers say ICU and emergency rooms in New York are “under siege” and running desperately low on personal protective gear and medical equipment, including ventilators.

“We have never seen anything like this, and we are so unprepared for the need that seems to grow daily,” an NYU Langone doctor told The Daily Beast on Thursday. “Honestly, I’m terrified.”

The U.S. now has more coronavirus cases than anywhere else in the world, with 86,012 positive diagnoses, according to Johns Hopkins University’s tracker.

Cuomo announced on Friday that the state was building another four emergency hospitals in convention centers, university stadiums, and shipping terminals, on top of four makeshift facilities already being built, to meet the 140,000 beds needed.

“We are doing things that have never been done before,” he said.