An ambulance service in England has apologised to the family of a pensioner who died after waiting nearly four hours for paramedics to arrive.
It took three hours 45 minutes for a crew to reach the home of an 81-year-old woman who rang 999 complaining of chest pains.
The emergency call was made at around 8pm on Tuesday and the woman was still alive when she spoke to the control room again at 9.47pm.
It took another two hours for an ambulance to arrive at her property in Clacton, Essex.
Paramedics then had to break into the home and by the time they reached the woman she had stopped breathing and could not be saved.
East of England Ambulance Service said it has launched an internal investigation into the incident.
Sandy Brown, deputy chief executive, said: "Our sincere condolences and apologies go out to the patient's family and friends and we are truly sorry for the ambulance wait that occurred at this incident.
"We have very publicly expressed how stretched the ambulance service is and the pressures our staff and the NHS as a whole have been under the past few days.
"As a trust, we have experienced our busiest days ever and we know our partners in the hospitals are in the same situation."
The service received more than 4,200 calls on January 2 and was also facing hospital handover delays "which can prevent us from responding as quickly as we need to", she added.
"Due to extremely high demand on the service and delays at accident and emergency units, we were not able to immediately dispatch an ambulance."
She added: "A clinician in one of our control rooms made a welfare call and spoke to the patient at 9.47pm and an ambulance crew arrived at the address at 11.46pm.
"The patient was found unconscious and not breathing and sadly died at the scene."
A union officer said the paramedics who responded to the call were "devastated" and "emotional".
Dave Powell, regional officer for GMB, added: "They're devastated because they're not in the job to find people dead, they're in the job to help people and keep them alive.
"It puts enormous strain and stress on people who are working really hard as it is.
"Three hours and 45 minutes is totally unacceptable for an elderly woman on her own with chest pains.
"Something has got to be done and the Government has got to wake up to this crisis."
He added: "I'm sure this case is much more widespread than the public is aware of."
The service previously said it has had to rely on taxis to take patients to hospital after struggling to cope with "incredibly high demand" and "extreme pressure" over the holiday period.
In another incident in Portsmouth, an 88-year-old woman died following a seven-hour wait for a bed.
Josephine Smalley spent five hours in an ambulance and another two hours on a trolley in a corridor at Queen Alexandra Hospital.
She died on New Year's Day, after having a heart attack and previously a stroke.