Mary Keegan was a "lovely, friendly woman" who was always "very protective of her kids", neighbours in Killakee Walk said.
She would "never close the front door" when her sons Glen and Andrew played outside their home, the end house of a quiet cul-de-sac.
A 41-year-old bank worker from Rathfarnham, she had lost a brother to illness, but more recently celebrated a happy event - becoming an aunt when her sister gave birth.
Just a few days ago, she left keys with a neighbour so that her husband - returning from a trip abroad - would be able to get into the house yesterday.
Her elder son, Glen, was a sports-loving 10-year-old who played hurling at nearby Scoil Treasa, where he was in fourth class. He was also due to appear last night in a school production of Snow White, an event cancelled yesterday as soon as the tragedy became known.
His brother, Andrew, who would have been seven next month, was described by neighbours as "very quiet", but he was a daily visitor to a friend's house at the end of the road, where he played.
He had not visited there since Friday, which was "unusual". He was in first class at Scoil Carmel, a sister school to Scoil Treasa, for the lower age-groups.
Their father, Brian Keegan, who was being comforted by relatives yesterday, is an engineer with the technical support unit of a Dún Laoghaire lawnmower business.
Neighbours said he was also a rallying enthusiast who worked on cars in the family garage during his spare time.
He had returned yesterday morning from a training trip to the US.