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Tributes to Prince poured in Thursday after his publicist confirmed the prolific pop singer, whose superstardom spanned more than three decades, had died.

"He was someone who combined not just rock and roll and R&B and funk, but he combined the traditions of protest music with dance music," Joe Levy, contributing editor at Rolling Stone magazine and host of "Incoming" on Spotify, told NBC News.

"He is someone whose creativity continued undiminished."

Fellow musicians were in disbelief that the 57-year-old, known for classics such as "Little Red Corvette" and "Purple Rain," had died.

"It’s really surreal," Aretha Franklin said on MSNBC. "I was coming out of my hotel and the doorman stopped me and asked me had I heard about Prince and it just blew me away. Unbelievable."

"There truly was only one Prince," she said.

Related: Prince, Iconic 'Purple Rain' Musician, Dies at 57: Publicist

"Numb. Stunned. This can't be real," tweeted Justin Timberlake.

"I can't believe it, I'm in total shock," tweeted Lionel Richie.

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A statement from President Barack Obama read in part: "Today, the world lost a creative icon. Michelle and I join millions of fans from around the world in mourning the sudden death of Prince.

“'A strong spirit transcends rules,' Prince once said -- and nobody's spirit was stronger, bolder, or more creative."‎

"The world has lost a great person. Not just the world of music but the world of man," musician George Clinton said. "It is a personal time of sadness for he was a close and dear friend. We stand with his family and fans alike in mourning this loss. "

Prince's legacy endured because his work was "groundbreaking," Levy said.

"His live performances were never less than mesmerizing and when he turned up for Grammy or Super Bowl performances, he set the bar that other people had to keep up with," he said. "He was making the music that everyone, no matter what kind of music they made, had to keep up with."

"I am stunned and heartbroken. I just spoke with him last night," actor Will Smith said on Facebook. "Today, Jada & I mourn with all of you the loss of a beautiful poet, a true inspiration, and one of the most magnificent artists to ever grace this earth."

The Rev. Jesse Jackson told the Associated Press that Prince "was a transformer," praising the musician for fighting for the freedom of artists and for himself.

"It’s easy to toss around the word 'iconic', but Prince truly epitomized the word to the very core of his being," Tommy Mottola, former CEO and chairman of Sony Music, said in a statement.

"The world is experiencing a tremendous loss today," he said.

"Prince was royalty to PETA," Lisa Lange, senior vice president of the animal rights group, said in a statement. "Prince's legacy of compassion and creativity will live on, and he will be sorely missed."

"Prince" quickly rose to one of the top trending topics on Twitter, with devotees quoting his music and mourning the loss of the seven-time Grammy Award winner.

Related: Prince's Career in Photos

"Tonight we're going to party like it's 2016, THE WORST YEAR EVER," tweeted one.

Musician Nile Rodgers tweeted: "I'll never forget my brother."

Director Spike Lee, who shared a photo of himself and Prince on Instagram and wrote, "I Miss My Brother. Prince Was a Funny Cat. Great Sense of Humor."

The Recording Academy said of the seven-time Grammy Award-winning music icon, "Never one to conform, he redefined and forever changed our musical landscape. Prince was an original who influenced so many, and his legacy will live on forever. We have lost a true innovator."

Celebrities and admirers shared their remembrances on social media:

Long Live The King. — Questlove Gomez (@questlove) April 21, 2016





In Minneapolis right now...and it's raining...



Prince... — Lupe Fiasco (@LupeFiasco) April 21, 2016

Today is the worst day ever. Prince R.I.P I am crying! — Boy George (@BoyGeorge) April 21, 2016

Prince the doves really are crying now. Listening to your music. Remembering you. #RIPPrince — Oprah Winfrey (@Oprah) April 21, 2016

I can't. I just can not. #Prince — shonda rhimes (@shondarhimes) April 21, 2016

I LOVED him, the world LOVED him. Now he's at peace with his Father. Rest in power, @prince, my brother. pic.twitter.com/ZN6cc3WWuF — Chaka Khan (@ChakaKhan) April 21, 2016

IN HONOR OF THE BEAUTIFUL ONE • #PRINCE • NOTHING COMPARES 2 U • 1958-2016 pic.twitter.com/utJvwpbryN — Apollo Theater (@ApolloTheater) April 21, 2016

Prince was an original who influenced so many, and his legacy will live on forever. pic.twitter.com/Lvlls0wiiZ — The GRAMMYs (@TheGRAMMYs) April 21, 2016

My heart is broken. There are no words.

I love you! — SheilaEdrummer (@SheilaEdrummer) April 21, 2016

R. I. P to the King Prince thank u for inspiring me to be a Musician First and using this tool to heal people — Wyclef Jean (@wyclef) April 21, 2016

He was a true legend and a musical genius! Prince could play every instrument with style and grace. — Earvin Magic Johnson (@MagicJohnson) April 21, 2016

My friend is gone...This is what it sounds like, when doves cry. He was my

dove...Stevie Nicks — Stevie Nicks (@StevieNicks) April 21, 2016