Four people, including an 11-year-old girl, a three-year-old boy and a man and woman in their 30s, have been found dead in a flat in Hounslow, the Metropolitan Police say.
All four at the property on Staines Road, Bedfont, were thought to be from the same family, said the force.
Police said they were called at 15:12 BST on Friday by a person "concerned about the welfare of the occupants".
After officers carried out a "forced entry" they discovered all four bodies.
The force described it as "a terrible incident" and revealed that no other parties were currently being sought.
Speaking at the scene, Ch Supt Sean Wilson, policing commander in west London, said there were "urgent inquiries" to locate and inform their next of kin.
He told reporters: "I believe we know who they are - four members of the same family - however, urgent inquiries are ongoing to locate and inform their next of kin and it would be inappropriate for me to name them at this time."
Post-mortem examinations are being arranged to establish their cause of death, he added.
It is understood that the property where the bodies were found comprises of two flats and they were discovered in the upstairs property.
A man who lives next door, who did not wish to be named, said: "They were just normal neighbours - we just had greetings here and there, that kind of stuff."
He added: "I came home from work and there were police everywhere. It was really busy. Nothing like that happens here. I have no idea what happened."
A female neighbour - who also did not wish to be named - said she exchanged pleasantries with the family and revealed that the woman was a "lovely mother with two young children".
She told the BBC the family were "absolutely gorgeous".
"It is very shocking," she added. "I still can't digest and understand what's happened and why (it has) happened, especially when there are little kids involved - it is just devastating."
'Shock and distress'
Felton resident Michael Oban, 56, who lives about half a mile from the property, said he was "disturbed" by the discoveries.
"Whatever the circumstances, the death of four people inside a property really is quite shocking," he added.
"You have two children in there. It's always distressing when you hear children lose their life."
In an earlier statement, Ch Supt Wilson explained that the police's "investigation is at a very early stage, and based on our initial inquiries, we are not currently seeking anybody else in connection with the incident".
"I know the shock and distress that this terrible incident will cause among the community in Hounslow and beyond," he added.
"I can assure local people that specialist officers are working to establish exactly what happened and I will provide further information as soon as I can."
He added: "I am also aware that this incident will be particularly upsetting for children, and I ask people to please be responsible about what they post on social media, including not naming or speculating as to the names of those who've died."
Hounslow council leader Shantanu Rajawat said the deaths had sent "shockwaves" through the community and he expressed his "heartfelt sympathies" to the family and friends of the deceased.
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2023-06-17 12:06:35Z
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