NEW YORK — New York’s governor issued an urgent appeal for medical volunteers Monday amid a “staggering” number of deaths from the coronavirus, as he and health officials warned that the crisis unfolding in New York City is just a preview of what other communities across the U.S. could soon face.

“Please come help us in New York now,” Gov. Andrew Cuomo said as the state’s death toll climbed by more than 250 in a single day to a total of more than 1,200 victims, most of them in the city. He said an additional 1 million health care workers are needed to tackle the crisis.

“We’ve lost over 1,000 New Yorkers,” Cuomo said. “To me, we’re beyond staggering already. We’ve reached staggering.”

Even before the governor’s appeal, close to 80,000 former nurses, doctors and other professionals in New York were stepping up to volunteer, and a Navy hospital ship, also sent to the city after 9/11, had arrived with 1,000 beds to relieve pressure on overwhelmed hospitals.

“Whatever it is that they need, I’m willing to do,” said Jerry Kops, a musician and former nurse whose tour with the show Blue Man Group was abruptly halted by the outbreak. He returned to his Long Island home, where he volunteered to be a nurse again.

Kops has been waiting to be reinstated since mid-March and said Monday that the state has sent him an email survey or questionnaire several times, without acting on it. In the meantime, he has been helping at an assisted living home near his house in Shirley, N.Y., and is considering sending his resume himself to hospitals.

In California, officials put out a similar call as coronavirus hospitalizations have doubled over last four days and the number of patients in intensive care has tripled.

“If you’re a nursing school student, a medical school student, we need you,” Gov. Gavin Newsom said. “If you’ve just retired in the last few years, we need you.”

With cases growing nationwide, President Donald Trump said the U.S. government is sending an additional 1,000 ventilators over the next two days to Michigan, New Jersey, Illinois, Louisiana and Connecticut.

“Challenging times are ahead for the next 30 days, and this is a very vital 30 days,” Trump told reporters. “The more we dedicate ourselves today, the more quickly we will emerge on the other side of the crisis.”

In Europe, meanwhile, hard-hit Italy and Spain saw their death tolls climb by more than 800 each, but the World Health Organization’s emergency chief said cases there were “potentially stabilizing.” At the same time, he warned against letting up on tough containment measures.

“We have to now push the virus down, and that will not happen by itself,” Dr. Michael Ryan said.

Three-quarters of a million people worldwide have become infected and more than 37,000 have died, according to a count by Johns Hopkins University.

The U.S. reported nearly 160,000 infections and over 2,900 deaths, with New York City the nation’s worst hot spot, but with New Orleans, Detroit and other cities also seeing alarming clusters.

“Anyone who says this situation is a New York City-only situation is in a state of denial,” Cuomo said. “You see this virus move across the state. You see this virus move across the nation. There is no American who is immune to this virus.”

Dr. Anthony Fauci, the U.S. government’s top infectious-disease expert, similarly warned that smaller cities are likely about to see cases “take off” the way they have in New York City.