Gardaí have described as "reckless and callous" an attack on a house in Co Offaly that killed a four-year-old boy and a 60-year-old woman.
They have been named as Mary Holt and Tadhg Farrell.
A murder investigation is under way into the fire in Edenderry, during which a woman in her 50s was also seriously injured.
Gardaí say they were alerted to a fire at the family home in Castleview Park shortly before 8pm yesterday evening.
Local fire services brought the blaze under control but were unable to save Ms Holt and Tadhg.
This afternoon their bodies were removed from the scene for post mortem examinations.
Watch: 'This was a reckless, callous and murderous attack on a family home', gardaí say
Another woman, in her 50s, was seriously injured and is being treated at the Midlands Regional Hospital in Tullamore.
All three are related and are from Edenderry, where a sense of shock and disbelief hung over the town.
Detectives are working to establish how the fire started and whether a petrol bomb was thrown at the house.
Gardaí will be going through CCTV and tracking the movements in and out of the estate last night to try and establish who was behind the attack.
Sources say it was clearly carried out by very violent and dangerous criminals, intent on causing serious harm.
One line of investigation is that it may have carried out by people involved in the drugs trade in the midlands.
However, the victims were innocent.
Minister for Justice Jim O'Callaghan strongly condemned what he described as a "deliberate callous attack" on the house.
"There is no place in a civilised society for such heinous violence. I join An Garda Síochána in appealing to anyone with information to come forward," the minister said.
Local Independent Ireland councillor Fergus McDonnell said the whole town is "absolutely distraught".
"I'm originally from up the road. I lived in this estate for 20 years up to a number of years ago," he said.
"I know all these people personally, and the families are ordinary, salt of the earth people, hard working and for something that just to happen, it's just unreal."
He said it is particularly hard to comprehend, given how close it is to Christmas.
"I've just spoken with two neighbours about all the craic they were having putting up the decorations," he said.
"A lot of houses here have external decorations and would get a lot of traffic coming in to admire them.
"Now we see the complete opposite happening after the last night, it's such a tragic loss of life."
Local Fianna Fáil councillor Claire Murray said her thoughts and prayers are with the family of the victims of last night's attack, adding that Edenderry is a darker place.
She said it is hard to put into words how devastated people are.
As gardaí carried out door to door enquiries, a technical and forensic examination of the scene continued.
Castleview Park is a long established housing estate close to the town and gardaí are appealing for witnesses to come forward.
At Edenderry Garda Station, Superintendent Liam Geraghty appealed for witnesses to come forward.
"This was a reckless, callous and murderous attack on a family home," he said.
"Gardaí want to speak with any person who was in the vicinity of Castleview Park or any of the adjoining roads or streets between 7pm and 8pm yesterday," said Supt Geraghty.
He said gardaí also want to speak to any person who was driving in the vicinity of Castleview Park or any adjoining roads between 7pm and 8pm yesterday and who may have any dashcam video or other images.
