A major investigation is underway following the death of six elderly patients at a Donegal nursing home.
Health authority bosses are trying to discover what caused the six deaths at a private facility in Buncrana.
A further 27 patients at the Nazareth House complex are being treated for a respiratory type illness which doctors fear may have caused the deaths.
Some members of staff have also contracted the virus and are being treated.
The Irish Independent newspaper reports that the virus may be a virulent strain of flu.
The six victims, all of them over 80 years of age, died within a 10 day period at the private nursing home.
Health experts from the local authority and from the patient watchdog group HIQA are at the 33 bedroom facility as they investigate the cases.
A spokesman for Ireland’s Health Service Executive said: “It has been reported that these deaths may have been as a result of a respiratory type illness.”
Ireland’s Minister for Health James Reilly has asked for a detailed report on the deaths after samples were sent to the National Viral Reference Laboratory for further analysis.
The 39 remaining residents are still at the private nursing home but all visits have been cancelled.
One woman, whose elderly mother is a patient, told the Independent of her real fears.
She said: “Nobody knows what is happening. All we know is that there is some kind of respiratory illness and we don’t know if it’s contagious or not. A lot of people are very worried.”
Local Buncrana Councillor Peter McLaughlin told the paper: “There are serious questions to be asked about when quarantine was introduced at the home, and whether patients were admitted after the outbreak began.
“There are a lot of questions which need to be answered now. We simply do not know how many more patients were admitted when there was an obvious risk.
“From what I understand there is a quarantine situation in place now but I would question if the damage has already been done.”