BOSTON -- Pop star Michael Jackson was pronounced dead by doctors Thursday afternoon after arriving at a hospital in a deep coma, city and law enforcement sources told the Los Angeles Times.

Paramedics reportedly administered CPR when the 50-year-old singer went into cardiac arrest on Thursday, TMZ reported.

A 911 was placed shortly before 3:30 p.m. from his Holmby Hills home in Los Angeles, TMZ reported. Jackson, who was not breathing when paramedics arrived, was rushed to UCLA Medical Center, according to the Times.

A Jackson family member told TMZ Jackson is in "really bad shape."

Jackson, who started singing professionally at age 11 as a member of The Jackson 5, has won 13 Grammy awards during his four-decade long career. Five of his solo studio albums have become some of the world's best-selling records.

Known as the "King of Pop," he has raised millions of dollars for charity, although controversy has marred his public image. He was accused of child sexual abuse in 1993, but the criminal investigation was closed due to a lack of evidence. Jackson was never charged.

He was arrested in 2003 on child-molestation charges and acquitted in 2005 after a trial in California.

Jackson has married twice and has three children.

NewsCenter 5 and TheBostonChannel.com will have more information when it becomes available.