Shelly Kelly, a nurse practitioner from Tulsa, Oklahoma, never imagined that on her first trip to New York City, she would be unable to visit some of the area's biggest attractions.

"I had no idea that on my first trip to New York I wouldn't be able to see a Broadway show. I wouldn't be able to go out to all the nice restaurants I've heard about. I wouldn't be able to see people around Times Square. It's completely different," said Kelly, who landed in New York on Sunday.

Beds are lined up in a tent as volunteers from the international Christian relief organization Samaritan's Purse set up an emergency field hospital in Central Park across from Mount Sinai Hospital in New York on Monday, March 30, 2020. Bryan R. Smith / AFP via Getty Images

Instead, Kelly will be among a few dozen nurses and doctors from Samaritan's Purse, a nondenominational evangelical Christian humanitarian organization, working at a field hospital set up in Central Park — across the street from Mount Sinai Hospital — for patients battling COVID-19, the disease caused by the coronavirus. The organization is led by Franklin Graham, the son of Billy Graham.

On Sunday, New York Mayor Bill de Blasio pledged to use every place needed to help people.

"This is the kind of thing you will see now as this crisis develops," he told reporters while discussing the field hospital in Central Park.

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It made for a jarring scene Monday.

"It's kind of surreal to see a field hospital sitting in the middle of Central Park," Kelly said. "I just don't think this is the way it was supposed to be my first time, but it's a pleasure for me to be here."

The field hospital will have 68 beds, 10 of them in a makeshift intensive care unit for patients who need ventilators. It took 48 hours to build and will be operational by Tuesday, said Melissa Nystrom, a spokeswoman for Samaritan's Purse, which is working with Mount Sinai Health System.

Seventy-two disaster assistance response specialists from Samaritan's Purse worked around the clock with local volunteers to build the hospital, Nystrom said.

Nurse practitioner Shelly Kelly will be working at the field hospital in Central Park in New York. Janelle Griffith / NBC News

"Just getting the permits to put up a field hospital in Central Park should've taken years," Kelly said, adding that with help from de Blasio and New York Gov. Andrew Cuomo, the hospital has "been up really fast."

"I think that just speaks to the resilience and the flexibility of our health care system here in the United States — that we can take down barriers like that and bring in a field hospital at a time when our health care system is overwhelmed," Kelly said. "It's just amazing to see the creativity and thinking outside the box that happens here."

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Cuomo said Monday that 1,218 people had died from the virus in New York state, up from 965 Sunday. A Navy hospital ship docked in Manhattan on Monday morning and is expected to provide relief for the city's overwhelmed hospitals.

"Those numbers are daunting," Cuomo said at a news conference. "It's continuing to move across the state of New York. Anyone who says this situation is a New York City-only situation is in a state of denial."

Denial is the last thing on the minds of Kelly or Dr. Elliott Tenpenny, director of international health at Samaritan's Purse.

"I know I'm going to be working in an ICU, and that's where a lot of the deaths happen, and so, yes, I am prepared for that," Kelly said. "As prepared as you can possibly be as a practitioner walking into that kind of situation."

Her previous assignments with the organization have taken her to the Philippines, Ecuador and the Democratic Republic of the Congo and twice to Iraq.

"This is an incredibly unique effort. We've been afforded the challenge by the governor's office, by the federal government, by our partnership with Mount Sinai, among others, to be able to do something that's really unprecedented here," said Tenpenny, who will be the team lead.

When Samaritan's Purse responds to disasters inside the U.S., like hurricanes, it's usually with general efforts after the fact. It has never before responded in a medical capacity within U.S. borders, according to Tenpenny and Kelly.

"Samaritan's Purse looks for where the need is greatest around the world," Tenpenny said. "Right now, that happens to be New York City."

The organization has another field hospital in Cremona, Italy, outside Milan, another hot spot of the COVID-19 virus, Tenpenny said, marking the first time Samaritan's Purse has had two emergency field hospitals running at the same time.

"We're looking for those needs and want to respond to those as quickly as possible," Tenpenny said.

Asked whether he was sought out by local or government officials, Tenpenny said, "We worked with the federal government and state government, who was able to hand us to the local government."

The field hospital in Central Park will have 60 to 70 medical staff, including nurses and doctors. Tenpenny said he could not provide specifics, but he said the nurses will outnumber the doctors.

"The truth is, no one knows how big this need is going to be or how long it's going to be present for," Tenpenny said. "Honestly, we hope it's very short and that New York City isn't suffering from this for very long. But we're here for as long as the need exists."