Five people have been killed after a blaze tore through two floors of a terraced home in Hounslow, west London, overnight on Sunday.
One man fled the Channel Close house before firefighters arrived and is being treated in hospital, London Fire Brigade (LFB) said on Monday.
His injuries are not believed to be life threatening.
Five people were found on the first floor and were pronounced dead at the scene. They are believed to be members of the same family, Metropolitan Police said.
Another person remains unaccounted for.
A neighbour told the Standard how a man was screaming and "absolutely lost" after the fire which is believed to have claimed the lives of his wife and children.
Felica Matei, 29, a jeweller said: "We saw the man who lived there with his wife and children. My daughter used to play with his daughter. There was fire in him and he was screaming something like 'my kids, my kids'.
"The family had been letting off fireworks earlier in the evening for Diwali but it was nothing to do with that as it was earlier than the fire. We are devastated."
A family friend said: “We are heartbroken. They are such a sweet family. The whole community is grieving.”
It is understood the family moved to the house relatively recently from Belgium.
Adelin Matei, Ms Matei’s partner, said: "They moved here from Belgium. They are a lovely family. They had Christmas lights around the front door. I don’t know whether the fire had anything to do with it. There was smoke in our house."
Ten fire engines and around 70 firefighters were called to the house fire just before 10.30pm on Sunday.
The ground floor and first floors of the mid-terraced house were destroyed and part of the roof was also damaged.
Police said in a press briefing at the scene said they were not actively seeking any suspect over the deadly blaze.
However, they emphasised they were ruling nothing out.
They said extra officers were being deployed to “reassure” the public.
London Fire Commissioner Andy Roe said: "This is a terribly sad incident and the thoughts of all of us at London Fire Brigade are with the family, friends and all those affected at this difficult time.
"Staff will be in the local community today to offer support and advice where needed.
"The welfare of our staff is very important and all those involved will be offered support from our counselling and trauma service."
Dileep Singh, 54, raced from Manchester to Channel Close where his brother in law was at home with his wife, three children and two adult guests.
He told the Standard: "I received a call and came as soon as I could with my wife we are desperate for information. My brother in law is alive but I don’t know what has happened to everyone else.
"We are desperate. I was told the fire came from outside from a bin. We are going to the hospital to try to get more information."
Metropolitan Police Chief Superintendent Sean Wilson, responsible for policing in Hounslow, said: "My thoughts are with the loved ones of those who very sadly lost their lives in this tragic incident.
"I don't underestimate the impact that this will have on the wider community and beyond. I understand that there will be a demand for answers and my officers are working to establish exactly what has happened."
Nearby properties were evacuated as a precaution.
Enquiries into the cause of the fire are ongoing. At this early stage in the investigation there have been no arrests, the Met said.
The fire was under control by 1.25am. Firefighters and police remain on scene on Monday morning.
There are road closures in place and people are advised to avoid the area where possible.
Fire crews from Heston, Southall, Twickenham, Hayes, Feltham and surrounding fire stations attended.
London Ambulance Service said it was called to Channel Close just before 10.30pm on Sunday.
"We sent a number of resources including five ambulance crews, an advanced paramedic, two clinical team managers, two incident response officers and members of our Hazardous Area Response Team," it said in a statement.
