Jackson Autopsy Put On Fast Track

Los Angeles officials have ordered an immediate autopsy for Michael Jackson, who died suddenly at 50 on Thursday afternoon.

Slideshow: Images Of Michael Jackson

Homicide and robbery investigators are leading the probe, but that is considered standard in any high-profile case.

The preliminary results may be available on Friday.

Jackson, 50, suffered a cardiac arrest Thursday afternoon and paramedics were unable to revive him. TMZ was told when paramedics arrived Jackson had no pulse and they never got a pulse back.

A source told TMZ that Jackson was dead when paramedics arrived.

Once at the hospital, the staff tried to resuscitate him but he was completely unresponsive.

A cardiologist at UCLA Medical Center tells TMZ Jackson died of cardiac arrest.

Michael is survived by three children: Michael Joseph Jackson, Jr., Paris Michael Katherine Jackson and Prince "Blanket" Michael Jackson II.

Thursday night at UCLA, a clearly emotionally distraught Jermaine Jackson, Michael's brother, began a press conference by saying, "This is hard."

Sighing in disbelief, he went on to say, "A team of doctors attempted to resuscitate him for a period of more than one hour and they were unsuccessful. Our family requests that the media please respect our privacy during this tough time. May Allah be with you Michael always. Love you."

Jackson had 13 number one hits during his solo career.

Fire department Capt. Steve Ruda told the L.A. Times that paramedics responded to a call at Jackson's home around 12:26 p.m. PT.

Ruda said Jackson was not breathing when they arrived. The parademics performed CPR and took him to UCLA Medical Center, Ruda told The Times.

TMZ.com first reported that Jackson was taken by ambulance to a hospital in Los Angeles in cardiac arrest and that paramedics administered CPR in the ambulance.

The 911 call came in at his Holmby Hills home in L.A.

His 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 26 million copies.

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.

Hundreds of people gathered outside UCLA Medical Center as word of his death spread.