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In this Dec. 1, 1984, photo, Michael Jackson is shown on stage at opening night of his Victory Tour at Dodger Stadium in Los Angeles. ((Lennox McLendon/Associated Press))

The death of Michael Jackson has left celebrities and fans shocked, and many of their tributes to the pop music icon are already pouring in to media outlets and social networking sites.

Quincy Jones, who helped arrange the music on Jackson's best-selling album Thriller and produced the Off the Wall album, told MSNBC News that he is "absolutely devastated at this tragic and unexpected news."

"For Michael to be taken away from us so suddenly at such a young age, I just don't have the words," Jones said. "I've lost my little brother today, and part of my soul has gone with him."

Jackson died Thursday afternoon after going into cardiac arrest at his Los Angeles home. He was 50.

Tweets from the music world

"Michael Jackson showed me that you can actually see the beat. He made the music come to life!! He made me believe in magic. I will miss him!" — Diddy

"Some lost Elvis Presley, and we lost Michael Jackson." — Wyclef Jean

"I am so grateful to have worked with the King (and always will be King) of the music industry. He was a gift to the world. He is a bright light, and I wouldn't be surprised if the world stopped spinning tomorrow." — Black Eyed Peas' Will.i.am

"Michael Jackson's done and accomplished so much that there's not even words to explain what he's done to urban music and pop music. Every artist that I personally know has been influenced by him." — Akon

"I never thought Michael Jackson would ever work with me. He actually sent for me, so that was kind of weird and cool at the same time." — T-Pain

"Thriller, musically, was amazing. It was just an amazing time." — Ciara

"[My favorite artist] of all time is Michael Jackson. I watched his DVD and almost cried. I would not know what to do if I ever met Michael Jackson. I would faint or I would cry." —The Veronicas

"As a child, Michael Jackson made me dance, dance, dance like a little bucktoothed fool. May his tired soul find peace and rest." — Bassnectar

Madonna told People.com that she "can't stop crying over the sad news."

"I have always admired Michael Jackson," the pop star said. "The world has lost one of the greats, but his music will live on forever! My heart goes out to his three children and other members of his family. God bless."

Lisa Marie Presley, who was briefly married to Jackson in the mid-1990s, said the news has left her "very sad and confused with every emotion possible."

"I am heartbroken for his children, who I know were everything to him, and for his family. This is such a massive loss on so many levels. Words fail me."

Actress Brooke Shields, who briefly dated Jackson, said her "heart is overcome with sadness for the devastating loss of my true friend."

'We have lost an icon'

Singer Dionne Warwick described Jackson as a friend and "one of the world's greatest entertainers" that she worked with.

"We have lost an icon in our industry," she said.

Neil Portnow, president and CEO of the Recording Academy, said in a statement that "rarely has the world received a gift with the magnitude of artistry, talent and vision as Michael Jackson."

Jackson's former publicist Michael Levine, who represented him when he was first accused of child molestation, said he was not surprised by the news.

"Michael has been on an impossibly difficult and often self-destructive journey for years," Levine said. "His talent was unquestionable but so, too, was his discomfort with the norms of the world. A human simply can not withstand this level of prolonged stress.''

Members of the public who were fans of Jackson's music also reacted to the news, but some of their admiration was tempered by the accusations of child molestation he faced even though he had been acquitted of the charges.

"I'm 42, and he was my idol when I was a child," Vincent Curry, a New York advertising account co-ordinator, said Thursday shortly after hearing the news.

"He was everything. I saw the Jackson Five perform live in Birmingham, Ala., when I was kid ... he meant the world to me then."

But Curry said his adoration of the pop star ended with allegations of pedophilia.

"Just this month, he was trying to line up children to perform with him. He didn't have a problem he sought to overcome. He had a sickness and wanted no cure."

As word broke of his unexpected passing just hours after another 1970s icon, Farrah Fawcett, succumbed to cancer, newspaper websites, message boards and the social messaging site Twitter were flooded with postings of grief and disbelief.

"OK, I am really having an emotional breakdown," tweeted Dinean Robinson of Elizabeth, N.J.

Crowds gathered outside the Los Angeles hospital where Jackson was transported after going into cardiac arrest at his home. Like many fans, Curry said he stood by Jackson until he found it impossible to do so.

"When I was a teenager and my friends turned to Prince and mocked Michael Jackson as a 'sissy' and repeated the very well-known rumour in the black community about how he wanted to get a sex change … I stood alone in his defence."

Eventually, Curry turned against the star as well.

"There's a saying, 'Success lets you be who you really are,' and he embodied that. It allowed him to engage in his darkest impulses, and they ultimately took him down."

With files from The Associated Press