- Video report by ITV News Social Affairs Editor Penny Marshall
The death toll from the Grenfell Tower fire is now believed to be "around 80" people.
The vast majority of those killed are from just 23 flats, police said.
Metropolitan Police Detective Superintendent Fiona McCormack said contact had been made with at least one person from 106 of the 129 flats in the building.
From those 106 flats, 18 people are dead or assumed dead. The remaining victims are thought to have been in the flats at the time of the fire and have not been heard from since.
The 23 flats which were said to have no survivors were between the 11th and the 23rd floor.
The true total of those killed in the devastating fire may not be known until the end of the year, police believe.
Police have been able to do a full visual search of all the flats, but some due to the devastating nature of the fire, some of the properties are too unstable for them to carry out further investigation.
Ms McCormack said a list of tenants provided to police by the Kensington and Chelsea Tenants Management Organisation, which managed the building, was "not accurate".
The Grenfell Tower investigation in numbers
- 129 - The total number of flats in Grenfell Tower.
- 23 - The number of flats in which police believe no-one survived during the fire.
- 106 - The number of flats where living occupants have been tracked down by police.
- 18 - The number of people living in or connected to those 106 flats who are believed to be dead.
- 80 - The total number of people police estimate died in the fire, meaning most were likely to be from the 23 flats with no survivors.
- 11th to 23rd - The floors on which the flats with no survivors were located.
- 26 - The number of calls to London Fire Brigade from people thought to be trapped in one of those 23 flats.
- 250 - The amount of detectives working on the investigation into the blaze.
- 600-plus - Calls made to 999 on the night of the fire.
She said: "We are many months from being able to provide a number which we believe accurately represents the total loss of life inside Grenfell Tower.
"Only after we have completed a search and recovery operation, which will take until the end of the year.
"What I can say is that we believe that around 80 people are either dead or sadly missing and I must presume that they are dead."
She added: "There are 23 flats that despite huge investigative efforts, we have been unable to trace anyone that lives there.
"At this stage, we must presume, that no-one in those flats survived, that includes anyone who lived there or was visiting them."
A couple who were missing and assumed dead had actually been on holiday at the time of the blaze, according to the detective.
"On the first day of our work we were provided with a list by the tenant management organisation of who they had recorded living at Grenfell Tower.
"We quickly identified by the end of the first day that this list was not accurate."
She added: "What we know is that it would be impossible for anyone to produce a list to show exactly who was at Grenfell Tower that night, that includes the people who were living there or who were visiting."