BUT gardai believe at this point they may have died as a result of carbon monoxide (CO) poisoning.
If this proves to be the case, the tragedy underlines the dangers of carbon monoxide to householders, particularly those living in older properties.
This highly dangerous gas is often produced from faulty heating appliances or in poorly ventilated rooms. Householders can safeguard against the substance by ensuring that chimneys and vents are kept clear, appliances are service and carbon monoxide alarms fitted.
For its part the Department of the Environment should conduct a publicity campaign to raise awareness of the dangers of carbon monoxide. Every death caused by this gas is preventable.