Staff shortages forced up to nine ambulances off the road in Auckland on Saturday night, as Omicron takes its toll on paramedics.
St John said it was the number of staff in isolation or ill that caused the situation, and warned the problem has been compounded by a general shortage of healthcare workers affecting the entire sector.
But workers are sounding the alarm that the issue is much bigger than Covid-19 and urgent intervention is needed.
St John paramedics are banned from speaking to the media - but concerns about ongoing delays in ambulance response times have prompted several share their concerns with Checkpoint.
They include Tom*, who was working in Auckland over the weekend, where staffing shortages meant they were nine ambulances down across the city on Saturday night.
Urgent code red calls were waiting up to 40 minutes and it was even longer for those supposedly less urgent.
"Orange, which is less immediately life threatening but we're still supposed to be there within 20 minutes - were just waiting hours and hours.
"A lot of patients were being told 'can you try to get in the car?' ... the staff, we're just worn out, we're just going around and around trying to get to who we can, and then apologising every time."
Tom said the issues filling shifts were getting worse, and he's not confident plans put in place by St John to manage the pandemic demand are working.
"They brought some staff up to have someone on these Covid trucks and they get paid money from the government - extra ... to run these special vehicles for Covid.
"But they just pull people off normal ambulances to do it and then don't cover those. It's just really robbing Peter to pay Paul, it doesn't really improve our staffing at all."
Working full time and constantly being asked to do overtime or cover other shifts is exhausting, he said, and he had lost faith in the organisation's senior leadership.
Tom said the government needed to take some accountability for the ambulance service.
"It seems like something needs to change, and there needs to be more oversight and more visibility."
Another paramedic, Ryan*, was also sounding the alarm. He said he felt overwhelmed with back-to-back 60-hour weeks, and the number of paramedics suffering burnout is the highest he's ever seen it.
He was both physically and emotionally exhausted from the need to race from one job to the next, and embarrassed at constantly having to apologise to patients and their family for the wait, but it was the shortage of time with patients' that really got to him.
"I'm trying to take my time, build a rapport with the families and provide care, knowing there's four other people that don't have a person there.
"It's a collective cry for help and not pointing the blame at anyone, but trying to show accountability - to the government to do something about it."
St John said 500 more paid frontline ambulance officers were introduced in the past five years and a major shake up to its leadership structure is in the pipeline.
It aims to have 84 more frontline leaders by October, meaning no line manager will have more than 70 direct reports - previously it was around 144.
It is also introducing a new critical care model, including higher skilled paramedics who will be sent to the most serious incidents.
While staffing shortages seem to be particualrly bad in Auckland, they're being felt across the country.
Manawatū paramedic Mark Quinn and secretary for the NZ Ambulance Association, he said they were three ambulances down on a recent night shift.
"10-15 years ago ambulances only attended road accidents and severe chest pains, and now we're doing everything from palliatives through to mental health, through to community-related things where there's no GPs."
He's not convinced that a government takeover is the answer to improve things - but admits delays are a problem at the moment.
"One of the things we could be looking to is not responding to low acuity jobs, that tie up amblances, and only leave us free for the real emergency."
In a statement, St John said its absences on Saturday night were due to illness and self-isolation, compounded by the healthcare professional shortage affecting the entire health sector.
It was down five ambulances between 6pm and midnight, nine down from midnight to 3am, and six down between 3am and 6am.
It said St John has not (as yet) identified any clinical adversity associated with delayed response times on Saturday night.
* Names changed to protect their identity.