LOS ANGELES (AP) -- Michael Jackson, the "King of Pop" who once moonwalked above the music world, died Thursday as he prepared for a comeback bid to vanquish nightmare years of sexual scandal and financial calamity. He was 50.

Jackson died at UCLA Medical Center after being stricken at his rented home in Holmby Hills. Paramedics tried to resuscitate him at his home for nearly three-quarters of an hour, then rushed him to the hospital, where doctors continued to work on him.

"It is believed he suffered cardiac arrest in his home. However, the cause of his death is unknown until results of the autopsy are known," his brother Jermaine said. Police said they were investigating, standard procedure in high-profile cases.

Jackson's death brought a tragic end to a long, bizarre, sometimes farcical decline from his peak in the 1980s, when he was popular music's premier all-around performer, a uniter of black and white music who shattered the race barrier on MTV, dominated the charts and dazzled even more on stage.

His 1982 album "Thriller" - which included the blockbuster hits "Beat It," "Billie Jean" and "Thriller" - is the best-selling album of all time, with an estimated 50 million copies sold worldwide.