Grenfell Tower blaze death toll rises to 79
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.