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NEW YORK CITY -- As New York City has become an epicenter of the global coronavirus pandemic, the staff of its hospitals have become “overwhelmed.”

“Things are pretty severe. I haven’t seen anything like this before. It’s brand new and we’re still trying to figure out how to treat it, so there are no ‘best practices’ in place. Things are changing daily and weekly,” a third-year internal medicine medical resident who is treating COVID-19 patients at NYU Langone Medical Center Tisch and Bellevue Hospitals told Fox News. “We are overwhelmed with new COVID-19 patients. People still have heart attacks. We have to be able to treat them too.”

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Some hospitals in the biggest city in New York state have been so overrun with dying patients that they’ve brought in refrigerated trucks to handle the bodies.

At Elmhurst Hospital in Queens, 13 people succumbed to the virus in one day.

The resident confirmed as “100 percent true” the horrors coming out of the Queens hospital from a doctor he went to medical school with, a third-year emergency medicine medical resident: “I urge people to stay home. We are still at a point where this is getting bigger each day.”

One doctor from NYU Langone said Bellevue has been in much worse shape, running out of ventilators. She said that at least one teenager without underlying medical conditions was on a ventilator for COVID-19.

Gov. Andrew Cuomo, again pleading for help in dealing with the coming onslaught, attributed the cluster to the city’s role as a gateway to international travelers and the sheer density of its population, with 8.6 million people sharing subways, elevators, apartment buildings and offices.

“Our closeness makes us vulnerable,” he said. “But it’s true that your greatest weakness is also your greatest strength. And our closeness is what makes us who we are. That is what New York is.”

City ambulances have seen a surge in calls, responding to nearly 5,800 on Thursday alone.

The city’s mayor, Bill de Blasio, tweeted Thursday evening: We're dealing with an unprecedented crisis in New York City. We are losing people every day. There are now 23,112 COVID-19 cases in New York City and 365 deaths. The next few months will be painful and stress our health care system like never before.”

While the city has meticulously tracked the outbreak, officials say they do not have numbers on how many health care workers are sick or dying.

Hospital operator Northwell Health said 155 of its 72,000 employees have tested positive for coronavirus. The New York State Nurses Association said at least 67 nurses had been infected. The union for the city’s EMS workers said more than 50 had tested positive and more than 400 are showing symptoms.

The number of people around the world who have contracted coronavirus has surged past 500,000, and the United States tops the list, according to a Johns Hopkins University tally.

That comes as U.S. deaths from the pandemic have now topped 1,100, in another grim milestone for a global outbreak that is taking lives and wreaked havoc on economies and established routines of life. Worldwide, the death toll climbed past 23,000, according to Johns Hopkins’ running count.

The resident told Fox News that a lack of medical supplies is adding to treatment delays.

“We have two masks that we use: the N95 and the regular surgical masks. We use the N95 for intubating patients with COVID-19 and we use them for 48 hours. The surgical masks are used for checking temperatures etc. and we use the same one for an entire week.”

The resident said about the masks they use: “We’re storing both types of masks in paper bags between patients and using them for as long as they’ll last. In the past, we typically used a new mask for each patient although this isn’t strictly necessary for N95s.”

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New York City medical professionals are looking for the following unused items:

N95 respirator (medical or industrial)

Gowns

Gloves

Surgical masks

The unnamed resident concluded: “I want to give a shout out to the NYC medical students who started the group PPE 2 NYC to help people donate unused Personal Protective Equipment or PPE to hospitals we are in great need.”

Fox News' Tamara Gitt in New York City contributed to this report.