Friends, Fans Mourn the Death of 'King of Pop' Michael Jackson

The tragic death of Michael Jackson has shocked the world, and messages of grief and appreciation have poured in from his family and close friends in Hollywood and around the globe.

"I am so 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," said Jackson's ex-wife Lisa Marie Presley, daughter of Elvis Presley.

"My heart is overcome with sadness for the devastating loss of my true friend Michael. He was an extraordinary friend, artist and contributor to the world. I join his family and his fans in celebrating his incredible life and mourning his untimely passing," Brooke Shields said in a statement.

Madonna also issued a statement, saying: "I can't stop crying over the sad news. I have always admired Michael Jackson. 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."

"Michael Jackson was my generation's most iconic cultural hero. Courageous, unique and incredibly talented. He'll be missed greatly,"said Russell Simmons, hip-hop entrepreneur and founder of Def-Jam Records.

Al Sharpton said he had spoken to Jackson recently about upcoming concerts planned in Great Britain.

"In my last conversations, including the conversations a couple of months ago when I was teasing him that I was coming to England to see him perform again, he talked about how many people had let him down, but I told him it didn't matter, he never let the fans down," Sharpton said at a news conference.

"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."

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."

Neil Portnow, the president of The Recording Academy, said Jackson's career "transcends musical and cultural genres and his contributions will always keep him in our hearts and memories."

“Rarely has the world received a gift with the magnitude of artistry, talent, and vision as Michael Jackson," Portnow said. "He was a true musical icon whose identifiable voice, innovative dance moves, stunning musical versatility and sheer star power carried him from childhood to worldwide acclaim."

Among the fellow musicians morning the loss was R&B singer Ginuwine, who told FOX News that words couldn’t describe how he felt at the news of Jackson’s death.

“When I heard that, I said, that can’t be true," he said. "You almost don’t want to believe it.”

But Hollywood heavyweight – and former Jackson publicist — Michael Levine told FOXNews.com he wasn’t surprised by the devastating 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.''

FOXNews.com also spoke exclusively to Jon Cohen, the former head of Jackson's label "A&R Records" who was still in close contact with and a good friend of the King of Pop.

"We spoke recently and he was in very high spirits. I wasn't aware of any heart problems and he was in good health," Cohen said. "I am in complete shock. He was so excited for the tour, it really would have been a comeback. He was rehearsing and up to the task. Michael was a very knowledgeable man. He was full of life and was such a visionary. More than anything, he loved his children very much."

"From his performances with the Jackson 5 to the premiere of the 'moonwalk' and 'Thriller,' Michael was a pop phenomenon who never stopped pushing the envelope of creativity," California Governor Arnold Schwarzenegger said in a statement.

"Though there were serious questions about his personal life, Michael was undoubtedly a great entertainer and his popularity spanned generations and the globe," Schwarzenegger said.

In New York's Times Square, a low groan went up in the crowd when a screen flashed that Jackson had died, and people began relaying the news to friends by cell phone.

"No joke. King of Pop is no more. Wow," Michael Harris, 36, of New York City, read from a text message a friend sent to his telephone. "It's like when Kennedy was assassinated. I will always remember being in Times Square when Michael Jackson died."

Benjamin Todd Jealous, president of the NAACP, issued a statement, saying: "Michael's example of musical artistry was rooted in the proud tradition of black American music. His career trajectory — from the working-class streets of industrial Gary, Ind., during the post-World War II boom, to the heights of the entertainment industry — is a classic example of black American achievement, and of the American Dream."

Click here for more from myFOXla.com.

The Associated Press and FOXNews.com's Hollie McKay contributed to this report.