A man, woman, and female child were killed in the blaze at a property on North Street in Langley Mill, Derbyshire. Five people were also injured. They were named locally as Amy Smith, 17, left, her baby Ruby Gaunt and family friend Ed Green.
Emergency services were called there at around 4am yesterday and found the house and a car parked outside “badly damaged” by fire.
Two people at the property affected by the fire and a further three residents from adjacent flats were able to escape.
A Derbyshire Police spokesman said: “Investigating officers say they are keeping an open mind as to the cause of the fire and have not ruled anything out at this early stage in the inquiry.
“Police are not in a position to give any further details of those who died in the fire as they are still tracing family members.
“Several neighbouring properties were evacuated as the fire caused a gas leak.”
One fire appliance was sent after Derbyshire Fire and Rescue Service (DFRS) was initially called at 3.59am to a car fire on North Street. A further three were mobilised following a call two minutes later reporting the house fire.
A DFRS spokeswoman said: “Tragically one male, one female and a female infant were unable to escape the fire and have been pronounced dead at the scene.
“Our thoughts and sympathies go out to the family and friends of the deceased.”
Neighbours said they had gone to help those stuck inside the house with ladders before emergency services arrived.
One man, who did not wish to be named, told the Derby Telegraph: “There were about 20 of us fetching ladders to reach the floors and we managed to get some people out.”
John Dunkley, a watch manager with Derbyshire Fire and Rescue Service, tweeted: “Terrible night shift. Thoughts with all personnel from all emergency services involved at Langley Mill this morning.”
Neighbour Paul Barber, 33, who lives in the flat next door to the one affected, said he and his wife were woken at 4am to banging on their door alerting them to the blaze.
Mr Barber said they ran outside and could see a “big glow” and high flames. He said: “People were screaming for help, it was very chaotic. I saw one person throwing their child out of the window on to a mattress to get him safe.
“It’s a big shame, they were a very cute family.”
East Midlands Ambulance Service (EMAS) said that it had treated five patients at the scene for smoke inhalation before they were taken to hospital.
Joe Garcia, EMAS associate director of operations, said: “We responded to a very tragic incident during the early hours where two adults and an infant died.
“Our crews were sent to a fire in Langley Mill after Derbyshire Fire and Rescue Service called for our assistance at around 4am. Three ambulances, a paramedic team leader and our hazardous area response team were sent to the emergency and provided medical support to five patients for smoke inhalation.
“Four patients were taken to Queens Medical Centre and one patient to Royal Derby Hospital. I would like to thank our crews for their hard work at this challenging job and express our condolences to the families of those involved.”