Wairarapa's emergency department hit an all-time staffing low on Sunday, with only two nurses rostered on the overnight shift.
Lucy McLaren, a nurse practitioner in acute services, said from midnight, the emergency department was running with 50 percent of its nursing staff, which was below safe striking levels - or below the minimum number of staff needed to safely operate during a workers' strike.
It was the first time staffing levels had gotten that low.
"It's incredibly dangerous and we're really worried about the safety of our patients and ourselves. We just don't quite know where to go or what to do next really, that's why we are speaking publicly.
"We've all been picking up extra shifts, doing extra nights, extra afternoons, coming in just to make sure that people get meal breaks - but we have so many off sick now and exhausted that there's just no spare staff."
McLaren was worried for her team - who were tired, at risk of making mistakes, not eating properly and not able to see their families - and the patients they were terrified of hurting.
"It's just awful, we've just had a potential stroke [victim] come in and it takes three or four people around the bed and we will only have two, so it's really scary."
The day shifts had been staffed by charge nurse managers, some who had been working for 10 or more days in a row, she said.
The staffing shortages during the night shift were set to continue for the coming week due to a number of staff off sick.
"No matter what we ask for or how loudly we say we are in trouble - no-one at the top seems to be hearing us," McLaren said.
The Wairarapa District Health Board has been approached for comment.
New Zealand Nurses Organisation (NZNO) president Anne Daniels said it was "extremely bad" for a hospital to have staffing levels that were below safe striking levels.
"Life preserving services during a strike is the bare minimum to keep the department safe and in that situation, lots of doctors and various other health professionals step up and actually fill the nursing gap."
Daniels said nurses were working overtime, double shifts, triple shifts, and on their days off - which was leading to them getting overwhelmed and unwell, so they were unable to come to work.
"We've got to the point where we absolutely don't have the resource to keep closing the gaps anymore and we've done it for too long, because of the decisions made by other governments and the current government and we can't keep doing it anymore."
A number of things needed to change, she said, but in the short term, the focus needed to be on keeping nursing staff as well as possible so they could continue to go to work.
Part of the problem was that part time and casual nurses were paid overtime, double time and triple time but full time nurses were not paid any extra for overtime which created a disadvantage.
"We need to have a system that actually promotes fairness, that promotes wellbeing for the nurses, and ensures retention of nurses right now, which is crucial to keeping the health system viable," Daniels said.
Daniels wanted to see conversations at a national level about how to support and incentivise nurses to stay in the job.
As the winter demand on hospitals across the country continued, Daniels said prevention was better than cure and people needed to do what they could to stay well along with wearing masks and hand washing.
"If you don't get sick, you're not going to need health care and then that's going to take the pressure off all our health care workers and our system."