A man and a woman, and two children, have died in the fire in Waterford City.
Gardai say two other children have been taken to hospital with critical injuries following the fire at the Birchwood estate on the outskirts of the city.
The area remains sealed off this morning with a large Garda cordon in place.
A Garda investigation is underway and the scene has been preserved for a technical examination.
Waterford TD David Cullinane, said the loss will be felt across the county.
"There is a real sense of heartbreak and grief and trauma that this community are experiencing.
"I'm very conscious that there will be a wider family as well. I knew the family involved.
"It's absolutely heartbreaking because this is a large family, which has deep roots right across Waterford city and county, so the grief will be spread right across the entirety of Waterford".
A support hub has been established for those affected by this morning's fire in Birchwood.
Waterford City and County Council is inviting anyone impacted to meet at the Butler Community Centre in the St. John's Park area of the city.
