Natalie Godfrey died and her five-year-old sister, Lucy, was badly burned in the blaze which broke out after the electricity meter had been turned off. The house in Great Chesterford, near Saffron Walden, Essex, was without power when fire fighters arrived.
The alarm was raised at 6am when the girls' 26-year-old mother, Denise, who is expecting twins, and her boyfriend, Granville Mullarkey, ran into the street screaming for help. By then smoke was pouring from the bedroom.
Lucy, who was rescued by a neighbour, Pat Henry, suffered burns to 75 per cent of her body. She and the two adults, who were shocked but unhurt, were taken to Addenbrooke's Hospital, Cambridge, where Lucy's father, Martin, was at her bedside.
Station Officer David Curtis, one of the first on the scene, said: 'The children were probably so bemused by the smoke that they had no chance to escape. The lesson to be learned here is for God's sake fit smoke alarms.'