A person has died in a fire at a disused hostel that left three other people injured, police have said.
Forty firefighters tackled the blaze at the building in Lower Clapton Road in Hackney, east London, just before 4am on Saturday.
The Metropolitan Police said four people escaped - three of them injured - but an unidentified body was inside the building, which was still too unsafe for firefighters to enter.
"At this stage the fire is being treated as unexplained," a Scotland Yard spokesman said.
"London Fire Brigade will be carrying out a joint investigation with the Metropolitan Police to establish a cause."
A man who jumped 25 feet from a window before firefighters arrived is in a critical condition in the Royal London Hospital with burns and injuries sustained in his fall.
A man and a woman who were rescued from the roof of a porch by firefighters were treated in hospital for smoke inhalation and were later discharged.
Another man escaped uninjured. All of them are believed to be aged in their 20s, Scotland Yard said.
A LFB spokesman said they had the fire under control by 8am
"Parts of the ground, first and second floors were badly damaged by the blaze, as well as part of the property's roof," he said.