Two children and a woman have died in a “devastating” flat fire, Cambridgeshire Fire and Rescue Service said.
A man managed to escape the flames, which engulfed the maisonette in Cambridge, and is being treated in hospital.
More than 30 firefighters rushed to attend the blaze in Sackville Close, King’s Hedges, in the early hours of the morning.
A man in his 30s managed to escape the flat before crews arrived.
Firefighters rescued two children, a boy and a girl, but despite efforts to save them they both later died in hospital.
Cambridgeshire Fire and Rescue Service said that a woman in her 30s also died at the scene.
The man suffered serious injuries and was taken to hospital where he remains in a critical condition, a spokesperson added.
Emergency services were called to reports of a flat fire at 1.08am on Friday morning.
Crews arrived to find smoke billowing from the ground and first floor of a two-storey maisonette.
Firefighters managed to stop the fire from spreading to neighbouring homes.
Area Commander Stuart Smith said: “This is a devastating and deeply upsetting incident that will touch many people. Our thoughts are with the relatives, friends and neighbours of the family. It’s just heartbreaking.
“We know this will have a huge impact on the local community and our fire safety team was in the area visiting residents yesterday to provide fire safety information and reassurance and will be returning next week.
“A fire like this is one of the toughest incidents you can attend as a firefighter and we’re looking after the welfare of all those who responded to or supported this incident.”
An investigation to establish the cause of the fire has been launched.
An East of England Ambulance Service spokesperson said: “Three ambulances, three Hazardous Area Response Team vehicles, two ambulance officer vehicles and response cars from the East Anglian Air Ambulance and Essex and Herts Air Ambulance were called out in the early hours of Friday June 30 to a serious house fire in Sackville Close in Cambridge.
“One woman had sadly died at the scene. One man with serious injuries was transported to Addenbrooke’s Hospital together with an infant and an older child – both children in serious conditions.
“An infant from an adjoining property was also transported to Addenbrooke’s Hospital for further assessment and care.
“The ambulance service would like to extend its deepest sympathies to all those affected by this tragic incident.”