Massive fire breaks out at luxury London hotel, officials say The cause of the fire was not immediately known.

Dozens of firefighters are battling a massive blaze that broke out at a luxury hotel in West London on Wednesday, officials said.

The London Fire Brigade said 120 firefighters and 20 fire engines were deployed to tackle a "very visible fire" at the 12-floor Mandarin Oriental Hotel in the affluent area of Knightsbridge, overlooking Hyde Park. The hotel has been evacuated.

The brigade said it has received some 40 calls about the fire, which is emitting "a lot of smoke." The first call came in just before 4 p.m. local time.

“The smoke from this large fire was very visible across Central London this afternoon, and we received a number of emergency calls," London Fire Brigade station manager Pam Oparaocha said. "Firefighters are working extremely hard to bring the fire under control. Crews wearing breathing apparatus are carrying out a search inside the building."

The London Ambulance Service sent multiple crews to the scene of the fire, including its hazardous area response team, according to assistant director of operations Graham Norton.

"We have not treated any patients but we remain at the scene as a precaution," Norton said.

Images from the scene showed vast plumes of black smoke billowing from the building into the London skyline.

The cause of the fire was not immediately known.

"Firefighters are likely to be there throughout the evening, and once the fire has been brought under control fire investigators will take over to establish how the blaze started," Oparaocha said.