by Cambridgeshire Constabulary said Gemma Germeney, 31, died at the scene on Friday, while Lilly Peden, eight, and four-year-old Oliver Peden died later in hospital.
Firefighters had pulled all three from the blaze at the flat in Sackville Close in King’s Hedges, Cambridge.
A man in his 30s remains in a critical condition. Specialist teams are investigating the cause of the fire.
The East of England Ambulance Service (EEAS) said an infant from an adjoining property was also taken to hospital for assessment.
Chelsea, 23, who lives in the close, said she was woken by screams and shouting and helped to get people out of neighbouring flats.
She said it was a “close community” that would pull together to help each other, adding that the “news was devastating”.
Cambridgeshire Fire and Rescue Service (CFRS) area commander Stuart Smith said six fire appliances attended the incident at about 01:10 BST on Friday and “were met with a serious intense fire in a maisonette-style flat”.
He said the fire remained the subject of an “ongoing investigation” and CFRS was working with police and specialist fire teams to “draw some conclusions”.
He said more information was expected to be released in the coming days, adding: “We won’t rule out anything.”
He said he was “really proud of the way our firefighters dealt with the incident” and the “effort and bravery on the night was incredible”.
“They did extremely well to confine the fire to the property and do all they could to rescue casualties from the building,” he said.
He added that the fire service had been giving reassurance and safety advice to people living nearby and urged people to have working fire alarms on every floor.
Flora Griffin, 28, who lives nearby, said all the emergency services were “working really hard and all together”.
“Our hearts go out to the family,” she said.
A representative from EEAS said the service wanted to “extend its deepest sympathies to all those affected”.
“Our deepest condolences and thoughts are with the family, friends and local community,” they said.
“This will have a huge impact on all of those, and we’ll do all we can to support the local community in the coming days and weeks as we continue our work in the area.”
A police representative said Cambridgeshire Constabulary’s “thoughts remain with the family, friends and the local community”.
