The music world is mourning the loss of soul and R&B icon Allen Toussaint. The legendary musician and producer, who is considered the impresario of the New Orleans music scene, died from an apparent heart attack after playing a concert in Madrid on Monday night (Nov. 9). He was 77 years old.

Toussaint’s daughter, Alison Toussaint-LeBeaux, confirmed the sad news to the New York Times. According to Spain's newspaper El Mundo, Toussaint went into cardiac arrest at his hotel but was revived by paramedics. Unfortunately, while en route to the hospital, he suffered another attack and died by the time the paramedics arrived at the emergency room.

Toussaint, a self-taught piano player, helped define the New Orleans sound as a songwriter and composer. He started his music career as a teenager during the 1950s, and released his first album -- a collection of instrumentals -- in 1958, under the alias Toucan. During the '60s and '70s, he was prolific with his songwriting and producing, having worked on songs like Ernie K-Doe’s "Mother-in-Law" and "Lee Dorsey’s "Working in the Coal Mine," among others.

One of Toussaint's biggest hits was as the producer of the landmark 1974 album Nightbirds from LaBelle. That album featured the group's most-well known hit, "Lady Marmalade." Toussaint also produced classics albums for the funk band the Meters, Etta James, Dr. John, Joe Cocker and others.

Toussaint's songs also have been heavily sampled by rap artists and singers alike. Most notably, Jay Z using Toussaint's 1965 song "Go Back Home" for "D'evils" and Amerie's "1 Thing" features a sample of the Meters 1969 song "Oh, Calcutta," which was produced by Toussaint.

Among Toussaint's accolades include an induction into the Rock and Roll Hall of Fame in 1988, the Louisiana Music Hall of Fame in 2009, and the Blues Hall of Fame in 2011. In 2013, he received the National Medal of Arts from President Barack Obama.

Mr. Toussaint is survived by his son, Clarence "Reginald" Toussaint; his daughter, Alison Toussaint LeBeaux; and several grandchildren. Funeral arrangements are pending.

Upon hearing the news of Allen Toussaint's death, artists from all music genres took to social media to express their condolences and to remember a talented musician who influenced the careers of countless performers.

Patti LaBelle, who worked with Toussaint as part of Labelle and as a soloist, issued a statement to Billboard.

"Allen was a gentle giant! Perceptive, kind and always open to your input and feelings," she said of the late musician. "He knew how to listen and never offended. He also introduced me to shrimp sandwiches, which I still love today!"

"Allen was one classy man and I will truly miss him! My condolences and prayers go out his family and all of his loved ones!" she finished.

Roots drummer Questlove went on Instagram and wrote a brief but informative tribute to Toussaint.

"This dude wrote some of your favorite music & you just didn't know it," he writes. "He effected SO many genres. That's how you know how potent and effective your art is: when you quietly change the scene [without] proper acknowledgement. If someone had the right to have KWest brag swag it was this man."

True indeed. Allen Toussaint will be sorely missed. May he rest in peace.

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