Roxbury, Connecticut - Stephen Sondheim, hailed as one of theater's "greatest geniuses," has died at the age of 91.

The creator of the musical Sweeney Todd died on Friday morning at his home in Connecticut, according to the New York Times.

The newspaper said the American composer's death was announced by his friend and lawyer, F. Richard Pappas, which he described as sudden.

British theatrical producer Sir Cameron Mackintosh, who named a venue after Sondheim in late 2019, said: "The theater has lost one of its greatest geniuses and the world has lost one of its greatest and most original writers."

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"Sadly, there is now a giant in the sky."

"But the brilliance of Stephen Sondheim will still be here as his legendary songs and shows will be performed for evermore."

"Goodbye old friend and thank you from all of us."

Barbra Streisand, whose album The Broadway Album featured lyrics written by Sondheim, tweeted: "Thank the Lord that Sondheim lived to be 91 years old so he had the time to write such wonderful music and GREAT lyrics! May he Rest In Peace."

Andrew Lloyd Webber described Sondheim as a "musical theater giant."

In a post on Twitter, Webber wrote: "Farewell Steve, the musical theatre giant of our times, an inspiration not just to two but to three generations. Your contribution to theatre will never be equalled. - ALW."

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Tony-winner Idina Menzel tweeted: "Goodbye dear sir. We will spend our lives trying to make you proud."

Anna Kendrick tweeted: "I was just talking to someone a few nights ago about how much fun (and fucking difficult) it is to sing Stephen Sondheim. Performing his work has been among the greatest privileges of my career. A devastating loss."

Tony winner Lea Salonga, who performed in last year's concert to mark Sondheim's birthday, tweeted: "Rest In Peace, Stephen Sondheim, and thank you for your vast contributions to musical theater. We shall be singing your songs forever. Oh, my heart hurts..."

Sondheim is known for other musical creations such as West Side Story, which he wrote the lyrics for, Follies, and Merrily We Roll Along.