In happier times, Diana Ross and Michael Jackson eased on down the road of stardom together.
But now, Ross can't help but sing a different tune.
"I can't stop crying, this is too sudden and shocking," said the former Supremes frontwoman, who costarred with Jackson in The Wiz and was often by his side during his red carpet heyday.
"I am unable to imagine this," Ross said. "My heart is hurting. I am in prayer for his kids and the family."
Her heart, and so many others.
Whitney Houston said it was "hard to express in words" what Jackson meant to her.
"He was my friend," the pop diva said. "He was one of the reasons I got into the music business. He inspired me. He taught me. He laughed with me. He paved the way for African American artists to be played on MTV which was huge.
"My heart is full of grief for his family and his children and I pray that they take solace in the incredible legacy of his music and art."
Added Mariah Carey, named Billboard's Artist of the Decade in 1999, 10 years after Jackson took the title: "My prayers go out to the Jackson family, and my heart goes out to his children. Let us remember him for his unparalleled contribution to the world of music, his generosity of spirit in his quest to heal the world, and the joy he brought to his millions of devoted fans throughout the world."
Jackson's fellow Motown legend, Smokey Robinson, said that it is "always hard to lose a friend.
"I will miss Michael and all that he brought to the world through his music and his creative genius. I know his legend will live on and the world will miss him dearly."
And while President Obama didn't speak out himself, Press Secretary Robert Gibbs says that our commander in chief told him that "obviously Michael Jackson was a spectacular performer, a music icon."
"I think everybody remembers hearing his songs and watching him moonwalk on television during Motown's 25th anniversary," Gibbs continued. "But the president also said he had aspects of his life that were sad and tragic. His condolences went out to the Jackson family and fans that mourn his loss."
Next-generation hitmaker Mary J. Blige said today, "One of my Angels has gone home. Michael, your love and greatness will live forever through me. I miss you and love you forever and ever. I'm so hurt and saddened."
Former Guns N' Roses guitarist Slash called Jackson "one of the most talented & dynamic performer/singer/songwriters" he ever had the pleasure of working with.
"Unfortunately, the controversy surrounding his personal life in recent years overshadowed his unparalleled contributions to the music world, which is a tragedy in as of itself. But, his music will live on forever no matter what & his memory will be adored & admired for years to come."
Meanwhile, though Macaulay Culkin's rep reiterated today that the former child star would not be issuing a statement, another pal from Jackson's past has reached out.
A rep for Webster star Emmanuel Lewis, who was known for palling around with Jackson back in the day, tells E! News she received a text from the diminutive actor this morning.
"It is very personal and very emotional to him and he is sincerely devastated at this time," the rep said.
"Love you Michael, you will truly be missed by the entire world. Your music will live on forever, truly timeless and iconic," Hilton wrote earlier this morning.