The death toll from the Grenfell Tower fire has risen to 79, police said.
Metropolitan Police Commander Stuart Cundy said five people had been formally identified and the rest were "sadly" missing presumed dead.
He told reporters the "awful reality" was that it might not be possible to identify all the victims.
Some families have lost more than one member, he added.
The announcement came ahead of a minute's silence to be held at 11am across all Government buildings to remember the people who lost their lives and all those affected by the fire in north Kensington last week.
Mr Cundy said the death toll may still change, but not as significantly as it has in recent days.
He fought back tears as he told reporters about the scene inside the 24-storey tower in north Kensington.
Footage from inside the gutted building has been released, showing the extent of the damage caused by the blaze.
He said it had been "incredibly emotional working in there", adding: "On Saturday I went in myself and went to the top floor.
"And it is incredibly hard to describe the devastation in some parts of that building."
Five people who had been reported missing after the disaster have been found safe and well, he added.
Mr Cundy said: "Sadly, as of this morning, I am afraid to say there are now 79 people who we believe are now dead or missing and we have to presume they are dead."
He said police had received some 70 pictures and videos of the fire from the public and urged them to send more as officers investigate the blaze.
He would not be drawn on the specifics of the criminal investigation of the fire, including whether anyone had been arrested or raids carried out.
As anger continued in the wake of the disaster, described by London Mayor Sadiq Khan as a "preventable accident", the Government announced on Sunday that those left homeless will be given at least £5,500 from an emergency fund.
Residents will be given £500 in cash followed by a bank payment for the rest from Monday, with the money coming from the £5 million fund announced by Prime Minister Theresa May on Friday.
Speaking outside Scotland Yard, Mr Cundy added: "I have investigated major crime for most of my service and I have seen some terrible things. But I don't think anything prepared me for what I was going to see when I was in there.
"It's hard to describe my feelings, because I cannot imagine, and I would not want to put myself in the position of those families who have lost their loved ones.
"But being with colleagues from the London Fire Brigade when I was in there, colleagues from the London Ambulance Service and other police officers, I think it's fair to say it is incredibly emotional working in there.
"But we will do it with our utmost professionalism and we will do everything we can as quickly as we can to locate everybody who is in there."
Homeless Grenfell Tower victims to receive £5,000 from Government fund
Victims of the Grenfell Tower disaster who have been left homeless will receive £5,000 in their bank accounts from today.
Theresa May announced the money will be extracted from the £5 million Government fund announced on Friday after the 24-storey block in north Kensington was ravaged by fire on Wednesday.
The tower was built in 1974 and contained 120 flats thought to be home to between 400 and 600 people.
Those who lost their home will also be given £500 in cash, the Government announced on Sunday.
No 10 said the £500 cash payment is already being handed out and further payments will be available from the Westway Centre and the nearby post office in Portobello Road.
Help will be given to residents who do not have bank accounts.
Mrs May said: "As we continue to respond to the needs of the community, our focus is on ensuring that all of those affected by this unimaginable tragedy get the right support as quickly as possible.
"My government will continue to do absolutely everything possible to help all of those affected through the difficult days, weeks, months and years ahead."
A residents group said while it welcomed the funding it had not been consulted before the announcement was made.
It said: "We naturally welcome funds for those in need, though this does show once more the tendency to sideline residents' views.
"At No 10 yesterday, the Prime Minister assured the group that from now on residents would be consulted on a coordinated relief effort. This has not happened with these funds."
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