More than 500 patients were waiting for an ambulance at a peak time this week as demand on the 999 service hits record levels.
One evening around 500 calls to the East of England Ambulance Service NHS Trust (EEAST) were “stacked”, meaning they had been answered but were waiting to be assigned an ambulance.
In the Norwich area alone more than 100 calls were waiting to be allocated at one point, according to information leaked to this newspaper.
In response, EEAST said it had "extensive plans" to deal with demand and is also recruiting extra call handlers.
It is also offering paramedics bonuses of up to £200 a day to work shifts.
An ambulance source said they wanted people to know how overwhelmed the service was, despite assurances from the NHS England chief on Thursday that the health service had never been overwhelmed by Covid.
Amanda Pritchard, the new chief executive of NHS England, conceded that the health service faced a "tough winter". But an ambulance worker, speaking on condition of anonymity, said it was far worse than that.
"People are dying because we can't get to them quickly enough," they said. "It can take up to 10 minutes to answer a 999 call at times.
"One of the problems is there are not enough call handlers and they are not paid well. You earn more working at Aldi."
The issue was raised in Parliament on Thursday and health secretary Sajid Javid admitted there were shortages of 999 call handlers.
The source added: "Sometimes we have more than 90 emergency calls just waiting to be answered and some of those calls are for ridiculous reasons.
"People phone saying they have a cough and very mild Covid or can't get their GP to call back - these are not life-threatening reasons to call.
"On the other hand, patients are having strokes and we can't get there fast enough. We are meant to get to the most urgent calls in seven minutes but sometimes we are not even answering the phone in that time."
They said there were often 300 to 400 calls which had been answered but were waiting for ambulances to arrive. This was backed up by multiple sources.
They added: "Some people are waiting up to 20 hours for an ambulance. I've finished shifts before and come in the next day to find some calls from my earlier shift are still there waiting. This is the worst anyone has ever seen it."
One Norwich man said last month he had been told to wait 16 hours for an ambulance and figures last week showed patients were waiting a record length of time.
In September EEAST received a record 132,000 emergency calls - almost 4,500 a day on average - and 1,000 more calls a day than September last year.
Sources said on the busiest days they could have between 6,000 and 7,000 calls.
Two separate workers said some of this was down to Covid. Cases have soared in the last month and people are ringing the 999 service after testing positive.
Meanwhile, paramedics are being offered bonuses of between £150 and £200 to cover shifts during the next two weekends because of a surge in calls expected over half term.
The trust told staff in an internal email that the incentives were for “key overtime shifts” and would support its “ability to deliver care to patients at identified pressure periods”.
Last week staff warned many of their colleagues had gone off on sick leave. Speaking to this newspaper as part of our series, NHS On The Brink, they warned morale was at rock bottom.
Marcus Bailey, chief operating officer at EEAST, said: "We are currently experiencing very high demand for our services which unfortunately means that some patients are waiting for longer while we prioritise life-threatening emergencies.
“We are continuing to ask the public to support us by using services wisely and only contact us if it’s an emergency. Local pharmacies or GPs can help with non-urgent issues, or NHS 111 is available online or via phone for urgent health advice.”
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here