Detectives investigating the Grenfell Tower fire have carried out three interviews under caution.
The Metropolitan Police said on Wednesday that the inquiry had moved into a new phase with the interviews, and that more will take place in the coming weeks and months.
Police are considering potential offences including gross negligence manslaughter, corporate manslaughter and breaches of the Health and Safety Act.
Seventy-two people were killed in the fire in June last year, with questions raised over flammable cladding used on the building and failures in fire safety arrangements.
Officers have spent the last year scouring the tower for forensic evidence and plan to hand back control of the building to Kensington and Chelsea council in early August.
Yvette Williams, of campaign group Justice for Grenfell, said she welcomed the news but that it was unfortunate it had taken so long to get to the interview stage.
‘Unfortunate it’s taken months’
"We do welcome that people have been interviewed under caution,” she told the Press Association.
"It's unfortunate that it's taken months after it happened, because if it had been somebody responsible like a member of the public, they would have been called in in June last year.
"But we do look forward to the police doing a thorough investigation and that they are already thinking ahead in terms of gross manslaughter charges can only be a positive thing."
Police handover of tower ‘a significant milestone’
Commander Stuart Cundy said: "The handover of Grenfell Tower by the police will only occur once we are entirely confident that all police work has been completed at the tower and handing the tower over to the responsible body will have no bearing on the ongoing criminal investigation.
"The concerns of the bereaved, survivors and residents as well as the wider community will be central to how the handover takes place.
“We recognise this will be a significant milestone and one that is bound to stir a range of emotions for all those affected by this tragedy.
"As part of our careful planning for a transition of responsibility, we are working closely with representatives from central government and London Councils."