LONDON, England (CNN) -- Firefighters are battling to contain a blaze at the Royal Marsden Hospital in London, one of the world's leading cancer treatment centers.

 

Crews were called to the hospital on the Fulham Road in west London after fire broke out shortly after lunchtime. In a statement, London Ambulance Service said there were no reports of casualties.

The London Fire Brigade told CNN the call came in at 1330 GMT and there were 15 fire engines and at least 75 firefighters on site.

The Ambulance Service said it had sent 15 ambulances to the scene along with a hazardous area response team and a fast response car.

Some patients have been evacuated from the top floor of the hospital, the Fire Brigade said. Fire Brigade station manager Guy Foster said that all patients had staff had been safely evacuated, the UK's Press Association reported.

TV pictures from the scene show heavy smoke billowing from the blazing roof as fire crews attempt to tackle the blaze.

Patients, some with blankets draped around their shoulders, others either on mattresses or in wheelchairs, had been led to safety as police closed off roads approaching the complex.

A hospital spokeswoman said patients were being sent to other hospitals nearby including Royal Brompton and the Chelsea and Westminster.
 
"We do not have details at the moment of how many patients that involves or how the fire may have started," she added.

Dr Peter Blake, who works at the hospital in radiotherapy, said he believed the blaze had caused widespread damage in comments carried by PA.

Blake added: "Unfortunately the fire is on the wrong side of the building as far as the wind is concerned. The roof is falling in, and there are bits falling off on to the outside."

He added: "We have practised a lot for evacuating people and I would be surprised if any of the patients had been hurt, but financially it's a disaster.

Blake said he thought the fire had started at the top of the building, where an air conditioning system is located.

"The problem now is that there is smoke coming through everywhere. I can't see that the theatre blocks can continue to function with no roof."

Pablo Pico, a worker at a nearby bookshop, told PA: "There is a lot of smoke and we can see a lot of ashes flying over. There are ambulances coming down the street still and helicopters overhead."

The hospital, which has a worldwide reputation for its treatment and study of cancer, treats more than 40,000 patients from both the UK and overseas each year.