The NAS sent out urgent messages on Thursday afternoon asking for any available staff to work overtime and to cover up to 19 staff who are out sick in the greater Dublin and Leinster regions.
Extra crew members were needed to cover all areas on Thursday night while shifts to be covered this weekend and into next week include Cavan, Drogheda, Ardee and Dundalk in Co Louth as well as Castleblaney in Monaghan and Navan, Co Meath
On Thursday night NAS desperately looked for staff to help cover half crews in Drogheda, Monaghan, Dublin South Central and Loughlinstown while full crews were missing to cover Wicklow, Maynooth, Longford, Athlone and Ardee.
According to the HSE's own NAS Capacity Action Plan, Level Three means that it's operational resourcing is between 10pc and 15pc less than affordable capacity to meet demand and between 10pc and 20pc of red or amber calls will receive a response in between one and two hours.
Level Three also means a loss of between 10pc – 15pc of planned fleet levels.
One staff member said: "The service is at breaking point, even before Covid-19 hit a lot of staff.
"Crews are blessed if they finish a 12 hour shift on time and not hours later. We are all burned out.
"One big thing needed is to educate people what an ambulance is for and when it is needed. Sometimes ambulances are used as a big yellow taxi which delays the service for real emergencies."
A statement from the HSE said: “The National Ambulance Service (NAS) has a surge plan in place which represents a national approach to capacity planning intended to enable a consistent sector approach to patient safety, risk mitigation as well as system and resilience understanding at times of escalating pressure.
"It provides systems partners and stakeholders with a clear visual representation of the issues faced and actions being considered and taken. The plan has four levels of escalation.
“Today, in response to significant levels of demand, which is also affected by COVID-19, NAS has escalated its surge response to Level Three which includes seeking support from external service providers.
“NAS are asking the public to help us help you by considering all care options available and only call 999 if it is an emergency.”