A murder investigation has been launched following a fatal arson attack at a house in Waterford City which claimed the lives of two adults and two of their children.

The man and woman have been named locally as Philip English and his partner Kim.

Two more of their children remain critically injured at Children’s Health Ireland in Crumlin following the fire at Birch Avenue in Birchwood shortly after 5am on Tuesday morning.

Gardaí say they believe the house was attacked by a person or persons unknown and that the fire was started deliberately.

The property has been declared a crime scene and is undergoing a technical examination by the Garda Technical Bureau.

The remains of the four deceased have been removed from the scene, with post-mortem examinations due to be carried out at University Hospital Waterford by Chief State Pathologist Professor Linda Mulligan and State Pathologist Dr. SallyAnne Collis.

An incident room has been established at Waterford Garda Station, with the investigation being led by the Serious Crime Unit and supported by the Garda National Bureau of Criminal Investigation.

Family Liaison Officers have also been appointed to support the bereaved family.

Gardaí are appealing to anyone who was in the Birch Avenue or wider Birchwood area between 4.30am and 5.30am on Tuesday morning to come forward.

They are also seeking dashcam footage or other images from anyone who was driving in the area during that time.

Anyone with information can contact Waterford Garda Station on 051 305300, the Garda Confidential Line on 1800 666 111, or any Garda station.