A mother and two children died in the blaze at the apartments.
The fire broke out at around 2.30am and is believed to have been caused by an electrical fault.
The apartment block here is a supported housing facility for victims of domestic abuse.
A woman and two young girls died in last night's fire – while a second woman and a 4 year old boy are in a critical condition.
The Taoiseach has offered his sympathies to the families of those killed.
A forensic examination of the scene is being carried out this afternoon as gardaí attempt to identify the exact cause of the fatal fire.
