John and Susan Cooper, 69 and 63, fell ill during their stay at the Steigenberger Aqua Magic Hotel in Hurghada and later died, with hundreds of Thomas Cook customers since removed from the resort.
Their daughter, Kelly Ormerod, was on holiday with them and her three children and said the family were in “utter shock” as they awaited results of postmortem examinations.
For now, Thomas Cook has said the “circumstances” of their deaths “are still unclear”.
Mrs Ormerod, from Burnley, told Lancashire radio station 2BR: “As a family we are devastated.
“Mum and Dad meant the world to me and the children, and we are in utter shock over what has happened and what is happening. Prior to going on holiday, Mum and Dad were fit and healthy. They had no health problems at all.
“Dad never went to hospital – he died in the hotel room in front of me. I went to hospital in the ambulance with Mum, where she passed away.”
Mrs Ormerod praised Thomas Cook for its response to the tragedy, which has resulted in 301 customers being taken out of the hotel and given the option of either moving to another resort or flying home early.
The travel operator said it had made the decision amid reports of a “raised level of illness among guests”.
Alison Cope, 44, from Birmingham, has been at the hotel for two weeks and seen five of her seven family members fall ill during that time.
She said: “The food is just disgusting, it’s under-cooked. I know so many people have been ill.
“Half the time we don’t know what it is and can’t eat it because it’s raw in the middle. We’ve spent almost two weeks at a five-star hotel eating bread and chips because we at least know what it is.”
In a statement, Thomas Cook said that customers who chose to come home would fly out on Friday, while the company would work with the hotel and support the investigation.
Mrs Ormerod said her focus was on getting her children home as soon as possible.
“All we want is answers about what has happened and a cause of death,” she added.
“I’d also like to thank people at home for their messages of love and support during this horrendous ordeal.”
Her mother worked at a Thomas Cook branch in Burnley.
Ingo Burmester, chief of Thomas Cook UK, described Mrs Cooper as a “loyal and long-serving” employee.
“We are deeply saddened by the deaths of two of our customers while on holiday in Hurghada in Egypt, one of whom was a loyal and long-serving member of our Thomas Cook family,” he said.
“Our focus is on fully supporting their loved ones.
“We are urgently investigating with the hotel and supporting the local authorities.”
It comes just a month after the company said the hotel had last been audited, receiving an overall score of 96%.
The listing for the hotel on the Thomas Cook website now says: “Sorry, there is currently no availability.”
The hotel is rated highly by travellers on TripAdvisor, with an overall score of 4.5 stars from more than 4,000 reviews