Pop icon Michael Jackson, whose rise to fame began some 40 years ago at Harlem's famed Apollo Theater, died Thursday afternoon after suffering an apparent heart attack in his Los Angeles home.

He was rushed, unconscious, to UCLA Medical Center shortly before 12:30 p.m. Pacific Standard Time, where doctors tried for more than an hour to revive him, UCLA officials said in a statement read to reporters by Jackson's brother Jermaine Thursday night.

His personal physician was with him at the time he was stricken, and paramedics tried to resuscitate him en route to the hospital, hospital officials said.

According to the Los Angeles Times, Jackson, who suffered a health setback last year, had been working diligently to get back in shape for a planned comeback tour next month. He reportedly passed a four-hour physical this spring.

Hospital officials said they believed Jackson suffered cardiac arrest, but that the exact cause of his death wouldn't be determined until results of the autopsy are known.

As the news spread Thursday afternoon, crowds congregated in front of the UCLA hospital awaiting word of the pop star's fate.

Jackson gained national attention as a youth in the 1960s, where he performed at the Apollo Theater as a member of The Jackson 5. Fans gathered Thursday evening in front of the theater to remember the performer and play his music.

The Reverend Al Sharpton, who said he was Jackson's friend for 35 years, spoke at a press conference outside the famous venue, recalling his friendship and spotlight-filled career.

"Michael Jackson made culture accept a person of color way before Tiger Woods, way before Oprah Winfrey, way before Barack Obama," said Sharpton. "Michael did with music what they later did in sports and in politics and in television. And no controversy will erase the historic impact."

Sharpton said he plans to reach out to the Jackson family to see if they would agree to hold a funeral service at the Apollo, similar to one held for the Godfather of Soul, James Brown, in 2006.

An entertainment giant whose influence rivaled that of Elvis Presley and The Beatles, Jackson rose to international fame in the 1980s as the "King Of Pop," known for his innovative choreography which included the "Moonwalk" dance step. His performances crossed racial lines, and his 1982 album "Thriller" remains one of the best-selling albums of all time nearly three decades after its release. In later years Jackson became a tabloid news standard with allegations of frequent plastic surgeries and charges of child molestation.

Fans who gathered in Times Square, including many who grew up listening to Jackson's music and watching his videos, said that they were shocked and saddened by the singer's sudden demise.

"I was thinking it's the end of an era," said one fan.

"It's sad. He's an '80s icon," said another. "I grew up listening to his songs. There's no place that you can go where you listen to Michael Jackson that you don't start dancing, and that's sad."