Pop star Michael Jackson died Thursday following a cardiac arrest at his home in Los Angeles, officials said. He was 50.
Paramedics were called to the singer's home around midday local time Thursday after he stopped breathing and suffered a suspected cardiac arrest.
He was rushed by ambulance to a local medical centre, but his death was announced shortly afterwards.
The star, who had a history of health problems, had been due to begin a series of comeback concerts in Britain July 13.
Concerns were raised last month when four of the concerts were postponed, but organisers insisted the dates had been moved due to the complexity of staging the show.
A spokeswoman for The Outside Organisation, which was organising the publicity for the shows, said she had no comment at this time.
Uri Gellar, a close friend of the star, told BBC News: "I'm devastated - it's very, very sad.
"I'm still trying to hold on to the glimmer that it's not true. It's too surreal for me to absorb that Michael is no longer with us."
DJ Paul Gambaccini added: "There's no doubt (his) records will be listened to for decades to come.
"There will be millions of people in the world who will have extreme emotional reactions."
US media reports said paramedics were called to the singer's house in Bel Air at midday.
They performed CPR on Jackson and rushed him to the UCLA medical centre.
Crowds have begun to gather outside the facility, whose emergency centre has been roped off by police.
Jackson began his career as a child in family group The Jackson 5.
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, according to the Guinness Book of World Records.
But 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 has 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.
I love michael jackson.His moves are so nice.