The East of England Ambulance service is to deploy more vehicles and staff after claims patients have died because of delays during the winter period.
An investigation has started into several serious incidents in the run up to Christmas and into the New Year.
Former health minister and North Norfolk MP Norman Lamb said ambulance delays are feared to have caused up to 81 patient deaths.
NHS England convened an emergency summit with the ambulance trust and other local health services to deal with concerns.
MPs held a debate on the crisis in the House of Commons on Friday afternoon.
The Labour MP for Peterborough, Fiona Onasanya, told the House that in 2014 a couple in her constituency lost their baby after a 999 call was downgraded.
Liberal Democrat MP Norman Lamb said he had seen a list of 40 cases of potential patient harm linked to response time delays at the East of England Ambulance Service Trust, including 19 cases where patients had lost their lives.
But he added he understood there were a further 120 incidents of potential patient harm, and the death total could exceed 80.
The summit drew up an action plan to deal with the issues faced by the ambulance service.
- Additional staff and vehicles to be drafted in from independent providers until Easter
- Ask local hospitals for a quicker handover of patients to release ambulances
- Better winter planning to forecast demand
- Improve staff health to boost staff availability
- Other health services asked to reduce the use of ambulances where there are 'safe alternatives'
Across England, the number of patients forced to wait in ambulances at A&E departments for more than half an hour rose to 11,100 last week. Of these, 2,100 patients had to wait more than an hour to be seen.
Weekly statistics released by NHS England show ambulance delays of between 30 and 60 minutes were up from 11,000 the previous week.
The East of England Ambulance Service covers Bedfordshire, Cambridgeshire, Essex, Hertfordshire, Norfolk and Suffolk.
- Click below to watch a report by ITV News Anglia's Kate Prout