Some Grenfell town victims may never be identified
Police fear they may not be able to identify everybody killed in the Grenfell Tower disaster.
Six bodies have so far been recovered from the gutted 24-storey tower, while 11 have been located inside but cannot be removed.
The death toll from the blaze is 17, but that figure is expected rise significantly.
Metropolitan Police Commander Stuart Cundy said: "It may be - and I just don't know - it may be that ultimately some victims remain unidentified.
"I won't know that until we've gone through the full recovery from Grenfell Tower and we know exactly what we've got and I anticipate that is going to take a considerable period of time.
"Not just the immediate recovery of the bodies we have found but the full search of that whole building we could be talking weeks we could be talking months - it is a very long process.
"There is a risk that sadly we may not be able to identify everybody."
His comments came as Prime Minister Theresa May ordered a full public inquiry into the disaster.
Mr Cundy's voice at one stage cracked as he spoke to reporters about the emotional toll the disaster had taken on him.
While refusing to speculate on whether the total number dead would reach triple figures, he said: "From a personal perspective, I really hope it isn't, for those of us that have been down there, it's pretty emotional, so I hope it is not triple figures, but I can't be drawn on the numbers."
A criminal investigation has been launched in the wake of the fatal fire amid increasing political pressure that those involved in the building's recent redevelopment should face prosecution.
"We as the police have started an investigation, I mentioned when I was down at the scene this morning that one of our very senior investigating officers is leading that for us," the commander said.
"We as the police, we investigate criminal offences - I am not sitting here and saying there are criminal offences that have been committed, that's why you do an investigation, to establish it.
"This will need to be a lot of work between us and other investigating agencies to establish what has happened and why and that is going to take a considerable period of time."
During the chaotic first day of the investigation, the police's casualty bureau was said to have received 5,000 calls.
Around 400 people were reported missing, but Mr Cundy downplayed the figure, saying it added up to more people than actually lived in the block. One person was reported missing 46 times, he added.
In other developments:
:: One of the first victims was named as 23-year-old Syrian refugee Mohammed Alhajali
:: A total of 30 people continue to receive hospital treatment, of which 15 are still in critical care
:: London Mayor Sadiq Khan and Labour leader Jeremy Corbyn called for a "proper investigation" into what went wrong
:: "Many" firefighters were described as being "traumatised" by what they faced
:: Labour's Tottenham MP David Lammy called for a criminal investigation into what happened
:: MPs gathered in Westminster Hall to question Fire Minister Nick Hurd about the blaze
:: The Queen paid tribute to the "bravery" of firefighters, and praised volunteers
:: Detective Chief Inspector Matt Bonner from the homicide and major crime command has been appointed to lead the investigation
:: Pop star Adele, who is originally from Tottenham in north London, also paid a low-key visit to the site in the early hours of Thursday to help with the relief effort
:: Scores of families are preparing to spend a second night in temporary accommodation.
Speaking from the scene in west London, Mr Cundy said: "Our absolute priority for all of us is about identifying and locating those people that are still missing.
"It would be wrong for me to get into numbers that I do not believe are accurate.
"We do believe that that number (17) will sadly increase."
The fire was finally extinguished shortly after 1am - a full 24 hours after the first alarms were raised - paving the way for tentative searches in Grenfell's worst-affected parts to begin once it is declared safe.
Explaining the nature of the investigation, London Fire Commissioner Dany Cotton said: "This is a large building, there will be a large amount of building work required internally.
"Before we do that, we are going to utilise some specialist dog training teams that we have, that will go through the building and the surrounding area looking for any identification of people.
"The benefit of using those dogs is clearly they are much lighter than people and they can cover a greater area in a very short space of time.
"I anticipate that London Fire Brigade will be on scene here for many days to come, working with our partners to ensure that we do the best for the people who are waiting for news of their loved ones."
She said "a good half" of the building had yet to be searched in detail, adding: "It is the upper floors which will be more challenging and will need some additional shoring up for us to be able to get in there."
Ms Cotton added: "This will be a detailed fingertip search.
"Obviously this will be a very slow and painstaking process."
More than £1 million has been raised to help those affected by the fire, with more than 60 tonnes of donations collected by one local mosque.
The six bodies which have so far been recovered from the scene were found outside the building, Mr Cundy said.
They have all been taken to Westminster Mortuary.
"Some of the bodies of those who have died are in safer bits of the building that we can recover," he said of the others.
"It may be that some of them we can recover today, some over the coming days but when we get to the more challenging floors the more higher up you go, I would not like to get drawn on how long that will take."
Every victim currently being treated in hospital has now been identified and reunited with their families, detective superintendent Fiona McCormack added.
Police urged anyone who is still concerned about a missing loved one to visit the reception area at the Westway Sports Centre, west London, or ring the casualty bureau on 0800 0961 233.
Those who have reported a friend or relative as missing but since been reunited with them are also asked to get in touch with police.