Around 125 firefighters have been on the scene to tackle a major blaze at Somerset House in central London on Saturday evening.
At least 20 fire engines were dispatched to the famous arts and culture center on the Beach after the alarm at around midday.
Crews are understood to be battling a fire in the roof of the historic building.
Witnesses reported seeing thick plumes of smoke visible as far as the south bank of the Thames.
Somerset House is closed as traffic builds up on the roads around it.
The center tweeted: “All staff and the public are safe and the site is closed.
“London Fire Brigade attended quickly and we are working closely with them to control the spread of the fire.”
The director of Somerset House Trust said the fire broke out in the west wing of the building and there is “no artwork in that area”.
Valuable works of art, including a Van Gogh painting, are undamaged and the whole community is “safe” after a fire tore through the roof of historic Somerset House.
London Fire Brigade said 125 firefighters and 20 fire engines were helping to tackle the blaze.
Somerset House Trust director Jonathan Reekie said the fire started in the west wing of the building, which is mainly made up of offices and “back of house” facilities, and that there is “no artwork in that area”.
The Courtauld Gallery, located in the north wing, houses a collection of famous paintings including Vincent Van Gogh’s 1889 self-portrait of himself with a bandaged ear.
Mr Reekie, 59, has been a director of the trust for 10 years and told the PA news agency: “I can confirm that around midday a fire was seen in one corner of the west wing, the site was immediately evacuated and the London. Called the Fire Brigade, who came very quickly indeed.
“Everyone is safe and for now we want to let the London Fire Brigade get on with their great work.
“The west wing is mostly offices and back of house facilities, there are no works of art in that area.”
Mr Reekie said he was not inside the building when the fire started.
The London Fire Brigade has warned people to stay away from the area.
From 1.55pm, the fire crews remained on the scene. London Fire Brigade said the cause of the fire is currently unknown.
There were no reports of injuries or casualties.
LFB tweeted: “Fifteen fire engines and around 100 firefighters have now been dispatched in response to the fire at #SomersetHouse.
“Crews are tackling a fire located in part of the roof of the building.”
Crews from Soho, Dowgate and Islington are among those sent to the scene, and 32m ladders were used.
A spokesman for Somerset House said: “Due to a fire in one small part of Somerset House, the site is currently closed.
“London Battle and other events will not be taking place today. We apologize for any inconvenience.”
Michelle Birkby, 50, who lives in London and is a writer, said: “I was walking on the South Bank, and I could smell smoke, I looked up and saw smoke coming out of a roof Somerset House.
“At first I assumed it was a barbecue in the yard, or some sort of event, but then I heard the fire engines, I realized the smoke was pouring out of control and Somerset House was on fire.”
The London Ambulance Service is urging people to avoid the area and for local businesses to keep their windows and doors closed.
Michelle Birkby, 50, who lives in London and is a writer, told the PA news agency: “I was walking along the South Bank, and I could smell smoke, I looked up and saw smoke coming out of the top of Somerset House.
“At first I assumed it was a barbecue in the yard, or some sort of event, but then I heard the fire engines, I realized the smoke was pouring out of control and Somerset House was on fire.
“It’s a place I visit often and I know it’s beautiful and I hope they can stop the fire before it does too much damage.”
A woman, who would not give her name but said she works at Somerset House, walked out of the cordon and told the PA news agency: “It’s fine, it’s localized to one area.”
Alan Robinson, 71, a Catholic priest who works nearby and lives in Covent Garden, said he was concerned about the “irreplaceable” art collection at the Courtauld Gallery.
He told the PA news agency: “The Courtauld Gallery is in there, I don’t know what the collection is worth, but it’s in the millions (of pounds) – things that can’t be replaced.”
A large poster of Vincent Van Gogh’s Self-Portrait with a Bandaged Ear was displayed on the railings, which is listed as part of the Courtauld collection on the gallery’s website.
Fire marshals in high visibility jackets escorted people from the center with signs that said “fire assembly point”.
At least five London Fire Brigade vehicles were stationed outside the arches of Somerset House on the Strand.
More fire engines could be seen inside the yard where thick smoke could be seen.