Pop star Michael Jackson has died in Los Angeles, aged 50.Paramedics were called to the singer's Beverly Hills home at about midday on Thursday after he stopped breathing.
He was pronounced dead two hours later at the UCLA medical centre. Jackson's brother, Jermaine, said he was believed to have suffered a cardiac arrest.
Jackson, who had a history of health problems, had been due to stage a series of comeback concerts in the UK, beginning on 13 July.
Speaking on behalf of the Jackson family, Jermaine said doctors had tried to resuscitate the star for more than an hour without success.
Jermaine Jackson on his brother's sudden death
He added: "The family request that the media please respect our privacy during this tough time."
"And Allah be with you Michael, always. I love you."
TV footage showed the star's body flown from UCLA to the LA County Coroner's office where a post-mortem is expected to take place on Friday.
Concerns were raised last month when four of Jackson's planned comeback concerts were postponed, but organisers insisted the dates had been moved due to the complexity of staging the show.
AT THE SCENE
Michael Jackson was brought here to the UCLA Medical Center in Los Angeles around 12 hours ago. Earlier there were several hundred people here, before it got dark - there was a sense of grief, of disbelief. But in the last few hours, these people have been singing his songs, dancing, there was a guy on a keyboard earlier, playing his songs for people to dance along to. This has turned into an impromptu celebration of Michael Jackson's music. He's the king of pop as far as they're concerned. They're still shocked by his sudden death but they're here because they want to show their support.
A spokeswoman for The Outside Organisation, which was organising the publicity for the shows, said she had no comment at this time.
Broadcaster Paul Gambaccini said: "I always doubted that he would have been able to go through that schedule, those concerts. It seemed to be too much of a demand on the unhealthy body of a 50 year old.
"I'm wondering that, as we find out details of his death, if perhaps the stress of preparing for those dates was a factor in his collapse.
"It was wishful thinking that, at this stage of his life, he could be Michael Jackson again."
Tributes have poured in from the entertainment industry. Sir Paul McCartney described Jackson's death as " sad and shocking".
The pair worked together on two hit tracks, Say Say, Say and The Girl Is Mine from Jackson's Thriller album.
He said " I feel privileged to have hung out and worked with Michael. He was a massively talented boy-man with a gentle soul.
"His music will be remembered forever and my memories of our time together will be happy ones.
"I send my deepest sympathy to his mother and the whole family, and to his countless fans all around the world."
Speaking outside New York's historic Apollo theatre, civil rights activist Rev Al Sharpton paid tribute to his friend.
"I knew him 35 years. When he had problems he would call me," he said.
"I feel like he was not treated fairly. I hope history will be more kind to him than some of the contemporary media."
Melanie Bromley, west coast bureau chief of Us Weekly magazine, told the BBC the scene in Los Angeles was one of "pandemonium".
"At the moment there is a period of disbelief. He was buying a home in the Holmby Hills area of Los Angeles and the scene outside the house is one of fans, reporters and TV cameras - it's absolute craziness.
"I feel this is the biggest celebrity story in a long time and has the potential to be the Princess Diana of popular culture."
Musical icon
Tributes from the world of music and film have already flooded in from celebrities including Madonna, Arnold Schwarzenegger and ex-wife Lisa Marie Presley.
Large numbers of fans have also gathered outside Jackson's home and at the UCLA medical centre with lit candles to mourn the star while playing his greatest hits.
Facebook groups have also been set up for fans to share their memories.
The singer's albums are occupying the top 15 slots of online music retailer Amazon.com's current best-seller chart, led by his 1982 smash hit Thriller.
Paramedics were called to the singer's house in Bel Air at 1221 (1921GMT) following an emergency phone call.
They performed CPR on Jackson and rushed him to the UCLA medical centre.
A spokesman for the Los Angeles Police Department said the robbery and homicide team was investigating Jackson's death because of its "high profile", but there was no suggestion of foul play.
Jackson began his career as a child in family group The Jackson 5.
MICHAEL JACKSON 1958-2009
Full name: Michael Joseph Jackson Born: August 29, 1958, Gary, Indiana, US Also known as: The King of Pop, Wacko Jacko Biggest hits: I Want You Back, Don't Stop Til You Get Enough, Billie Jean, Bad, Black or White, Earth Song
He then went on to achieve global fame as a solo artist with smash hits such as Billie Jean and Bad.
Thriller, released in 1982, is the biggest-selling album of all time, shifting 65m copies, according to the Guinness Book of World Records.
He scored seven UK number ones as a solo artist and won a total of 13 Grammy awards.
"For Michael to be taken away from us so suddenly at such a young age, I just don't have the words," said Quincy Jones, who produced Thriller, Bad and Off The Wall.
"He was the consummate entertainer and his contributions and legacy will be felt upon the world forever. I've lost my little brother today, and part of my soul has gone with him."
The singer had been dogged by controversy and money trouble in recent years, becoming a virtual recluse.
He was arrested in 2003 on charges of molesting a 14-year-old boy, but was found not guilty following a five-month trial.
The star had three children, Michael Joseph Jackson Jr, Paris Michael Katherine Jackson and Prince Michael Jackson II.
He is survived by his mother, Katherine, father, Joseph and eight siblings - including Janet, Randy, Jermaine and La Toya Jackson.
