LONDON -- A fire broke out at Buckingham Palace Sunday, forcing the evacuation of hundreds of people and marring the high-spirited, four-day celebration of Queen Elizabeth II's 50 years on the throne.
The London Fire Brigade said no members of the royal family were in the palace at the time of the fire, which police said was not intentionally set.
The cause, however, had yet to be determined.
The evacuation disrupted preparations for a star-studded pop music concert planned on the palace grounds Monday night. News reports said it was the first time the palace had been evacuated since World War II.
Ozzy Osbourne had just finished rehearsing his 30-minute set when the blaze began, and the British Broadcasting Corp. reported that those evacuated from the area around the palace included the musicians Phil Collins, Eric Clapton and Queen guitarist Brian May. It wasn't clear if Osbourne was evacuated.
The fire in a roof apartment was reported at 6:38 p.m. and was brought under control an hour and a half later, said Colin Williamson, a Fire Brigade spokesman. Workers were allowed back into the palace at 9.40 p.m.
Two areas of ceiling were damaged and water from burst pipes soaked some carpets at the palace, which has served as the official London residence of Britain's sovereigns since 1837.
Fire crews respond
When the fire was at its height, smoke poured from one area of the roof as firefighters with masks, air tanks and hoses worked nearby. Twenty fire engines rushed to the palace, Williamson said.
The volume of smoke diminished about an hour after the blaze was first reported. The evacuation had been a precaution, police said.
One firefighter was hit by a piece of equipment and suffered cuts and bruises around his eye, firefighter Steve Newman said, but there were no other injuries.
The palace said in a statement that a fire alarm system had detected the flames in a flat above the East Gallery, a large corridor that connects the palace ballroom to the state rooms.
The state rooms are at the heart of the palace and are used regularly by the queen and other royals for entertaining. Investitures are often held in the ballroom, which first opened in 1856.
Eighteen royals and 12,000 guests attended a spirited classical music concert on the palace grounds Saturday night and excitement was already building for Monday's show, which was expected to be a high point of the long Golden Jubilee weekend.
Most of the rehearsing artists remained on the palace grounds, away from the building, and concert preparations resumed at around 8:20 p.m. -- with firefighters watching from a balcony -- when former Beach Boy Brian Wilson took the stage.
Paul McCartney and Annie Lennox are among the others slated to perform before a crowd of 12,000 people and a live television audience.
"There is an enormous crowd of extremely famous people here sitting on the lawn chatting on their mobile phones," May told the BBC while the fire was still burning. "Everyone is being patient because we know things have to be done in the right way."
The Queen guitarist was scheduled to open the outdoor show by playing "God Save the Queen" while standing on the palace roof.
The palace said the concert would go ahead as scheduled.
"There is absolutely no question of it not" going on, a spokesman said on condition of anonymity.
The show was expected to be the most popular event in four days of Golden Jubilee celebrations, which are also scheduled to include street parties around the country and a royal procession to a service at St. Paul's Cathedral on Tuesday.
The damage caused by Sunday's fire did not appear to be nearly as bad as that done by two earlier palace blazes, at Windsor Castle in 1992 and at Hampton Court Palace in 1986.
Sir Hugh Roberts, director of the royal collection, was inspecting artworks and other valuable items for signs of damage, and the palace said two paintings were removed as a precaution.
Roberts told Prince Charles about the fire, and a spokeswoman said the heir to the throne was "shocked but relieved" that no one was seriously hurt.
The Windsor Castle fire gutted 100 rooms, caused tens of millions of dollars in damage and contributed to the difficulties of the year Elizabeth dubbed her "annus horribilis."
In 1986, fire wrecked a wing of Hampton Court Palace and killed one resident.
Until early evening, Sunday had been the quietest day of the jubilee celebrations.
The queen greeted hundreds of well-wishers who gathered at Windsor Castle to watch her arrival at a special church service as other members of the royal family worshipped around the country.
Elizabeth, 76, was 25 when she became queen upon the death of her father, George VI, in 1952.