Michael Jackson, the sensationally gifted child star who rose to become the "King of Pop" and the biggest celebrity in the world only to fall from his throne in a freakish series of scandals, died Thursday. He was 50. Jackson died at UCLA Medical Center in Los Angeles. Ed Winter, the assistant chief coroner for Los Angeles County, confirmed his office had been notified of the death and would handle the investigation. The circumstances of Jackson's death were not immediately clear. Jackson was not breathing when Los Angeles Fire Department paramedics responded to a call at his Los Angeles home about 12:30 p.m., Capt. Steve Ruda told the Los Angeles Times. The paramedics performed CPR and took him to UCLA Medical Center, Ruda told the newspaper. 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" remains the biggest-selling album of all time, with more than 100 million copies worldwide. He also starred in the 1978 blockbuster film, THE WIZ based on a 1974 Tony Award, theatre play, playing the scarecrow. The public first knew him in the late 1960s, when as a boy he was the precocious, spinning lead singer of the Jackson 5, the music group he formed with his four older brothers. Among their No. 1 hits were "I Want You Back," "ABC," and "I'll Be There." He was perhaps the most exciting performer of his generation, known for his feverish, crotch-grabbing dance moves and his high-pitched voice punctuated with squeals and titters. His single sequined glove, tight, military-style jacket and aviator sunglasses were trademarks second only to his ever-changing, surgically altered appearance. "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." "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." Jackson ranked alongside Elvis Presley and the Beatles as the biggest pop sensations of all time. In fact, he united two of music's biggest names when he was briefly married to Presley's daughter, Lisa Marie. But as years went by, Jackson became an increasingly freakish figure - a middle-aged man-child weirdly out of touch with grown-up life. His skin became lighter, his nose narrower, and he spoke in a breathy, girlish voice. He surrounded himself with children at his Neverland ranch, often wore a germ mask while travelling and kept a pet chimpanzee named Bubbles as one of his closest companions. In 2005, he was cleared of charges he molested a 13-year-old cancer survivor at Neverland in 2003. He had been accused of plying the boy with alcohol and groping him. The case took a fearsome toll on his career and image, and he fell into serious financial trouble. Jackson was preparing for what was to be his greatest comeback: He was scheduled for an unprecedented 50 shows at a London arena, with the first set for July 13. He was in rehearsals in Los Angeles for the concert, an extravaganza that was to capture the classic Jackson magic: showstopping dance moves, elaborate staging and throbbing dance beats. Singer Dionne Warwick said: "Michael was a friend and undoubtedly one of the world's greatest entertainers that I fortunately had the pleasure of working with we have lost an icon in our industry." Hundreds of people gathered outside the hospital as word of his death spread. The emergency entrance at the UCLA Medical Center, which is near Jackson's rented home, was roped off with police tape. "Ladies and gentlemen, Michael Jackson has just died," a woman boarding a Manhattan bus called out, shortly after the news was announced. Immediately many riders reached for their cell phones.

MADONNA: "I can't stop crying over the sad news. I have always admired Micheal Jackson. The world has lost one of the greats but his music will live forever."

LIZA MINNELLI: "He was a kind genuine and wonderful man. He was also one of the greatest entertainers that ever lived. I loved him very much and I will miss him every remaining day of my life."

CELINE DION: "I am so devastated by this terrible news. From the beginning of my career, he was my idol in show business. He was a genius and an incredible artist."

JAMIE FOX: "You cannot say enough about what he has given us musically and culturally. We take for granted people like him. All he wanted to do was give us great music and that's what he did. Every song he sang was dedicated to us."

SMOKEY ROBINSON: "The world is mourning the loss of his talent and people will miss his music. Micheal Jackson was one of the most intense, dynamic talents he ever live. He is Micheal Jackson."