Firefighters have tackled a major blaze at a Royal Academy of Arts (RA) building in central London.
The fire took hold at a building owned by the Royal Academy
The fire took hold at Burlington Gardens in Piccadilly - one of London's most prestigious shopping areas - creating huge amounts of smoke.
The RA said the building, formerly the Museum of Mankind, is currently empty and describes it as a "separate site". The main building was evacuated.
Sixty firefighters tackled the fire before it was brought under control.
Eye-witness Rachael White, 29, described seeing grey smoke billowing from the building behind the arts academy and a strong smell of burning in the air.
Another witness, Shannon Gordon, told BBC London: "All of a sudden I looked up and there were more flames... then the big bang was when the roof collapsed."
The building which caught fire, 6 Burlington Gardens, was adjacent to but separate from the main RA building - which was evacuated and closed for the day.
It is hoped it will re-open on Wednesday. Several roads in the area are likely to remain shut on Tuesday evening.
The smoke can be seen across central London
The Saatchi gallery has been preparing a major exhibition on American art in the Burlington Gardens building and has said it may have to postpone the opening, which was due for 6 October.
MaryAnne Stevens, RA acting secretary, said: "The carefully coordinated emergency procedures of the Royal Academy, and the effective management of the incident by the fire and police services, appear to have limited the damage to one gallery and the roof."
She thanked the emergency services and said the main site would be open on Tuesday.
A fire brigade spokesman said there was significant damage to the roof of the building - it is not known what caused the fire, on the west corner of the roof.