The mothers of the children were both caught up in the tragedy. One of them leapt from a first floor window of the house in Co Durham to escape the flames, leaving her three-year-old son inside.
The other, who had earlier dropped off her sons - one just nine weeks old, the other aged two - returned during the blaze. She was hysterical and fire officers had to restrain her.
The grandmother shared the three-bedroom end-of- terrace house in Holly Hill, Shildon, with the daughter who escaped and her grandson.
The family was trapped as flames and thick, black smoke engulfed the house at 10.30am.Neighbours tried unsuccessfully to fight the fire. Three search and rescue fire teams entered the house, only to find the four bodies downstairs.
"When we arrived, the house was alight from end to end with flames shooting out of the windows and doors," said Alan Wray, of Durham fire brigade. "Three fire crews entered the property [to] search but it became obvious that the chance of rescuing anyone was very slim.
"While firefighters were tackling the blaze the mother of the other two children, and sister of the woman who escaped, returned. She had to be held back as she was hysterical.
"It's very unusual to have a fire of this scale during daylight hours. We are looking for signs of anything that might have accelerated it. There are no signs of what started the fire."
Jane Wilson, who lives near by, said that she had known the woman who died for more than 35 years. "We grew up together, she was a lovely woman who loved her grandchildren," she said. "They were a very close family. It was her birthday next week and we were going to go out for a meal."
n An elderly couple, killed when a fire swept through their home, may have been the target of an arson attack because they kept 19 pet cats. Neighbours suggested that Charles O'Gorman, 70, and his wife, Margaret, 69, of Ellesmere Port, Cheshire, had been the victims of a hate campaign by some people living locally. Police are investigating.Reuse content