Almost 100 firefighters are currently tackling a blaze at a luxury London hotel.
London Fire Brigade said 20 engines and 120 firefighters and officers had been sent to the scene at the Mandarin Oriental Hotel, in Knightsbridge, as huge plumes of smoke could be seen rising into the sky.
LFB said the blaze was “very visible” and they had received more than 35 calls about the incident so far.
The hotel has 12 floors, the brigade added.
We've now got 20 fire engines and around 120 firefighters and officers tackling a fire on the roof of a hotel in #Knightsbridge https://t.co/Q8RMsTDSTf © @jackwmartin_ pic.twitter.com/npRctIYOvk— London Fire Brigade (@LondonFire) June 6, 2018
A statement said: “The Brigade was called at 3.55pm. Fire crews from Chelsea, Kensington, Hammersmith, Battersea and other surrounding fire stations are at the scene.
“The cause of the fire is not known at this stage.”
Several witnesses have been posting videos and images of the incident.
A hotel spokesman said: "We are aware that there is a fire at Mandarin Oriental Hyde Park, London, and that the fire brigade is at the hotel.
"As the situation is still unfolding, we have no further details to share at this time, but will provide an update soon."
Staff from the Mandarin Oriental Hotel have been evacuated to Hyde Park where they were being given bottles of water.
One worker, who asked not to be named, said: "The fire alarm started and everybody was told to get outside.
Jack Martin, a 21-year-old student from Peckham, said he was coming out of Knightsbridge station when he saw a "huge billow of smoke".
He told the Press Association: "I obviously was quite shocked when I saw all that smoke.
"But they were evacuating the building when I arrived, there were a fair amount of staff and guests and it was all fairly orderly.
Emergency services had since cordoned off the road, he said, and although there were ambulances present he had not seen any signs of injury.
"I would say the fire is under control now. I can't see any smoke, there are firefighters and the whole building is dripping wet right now," he added.
Penelope Evans, 50, from Battersea, south London, was shopping in Harrods when she noticed the thick smoke as she was leaving.
"I saw all this black smoke coming from the sky, it was covering everything and the smell was horrendous.
"It was like people were in shock, everyone immediately just started leaving the street and the area.
"There were hundreds of fire engines, ambulances, police racing by and helicopters overhead.
Just evacuated Mandarin Oriental hotel to see this.... absolutely crazy! So impressed by the organisation in bringing everyone to safety #knightsbridge #mandarinoriental pic.twitter.com/1837pi4uoD— Anna Whiteley (@AnnaWhiteley) June 6, 2018
- Digital Desk and PA