Musicians around the world are mourning the death of Fleetwood Mac co-founder Peter Green.

Green, who was 73, died in his sleep, his family confirmed in a statement released today.

“It is with great sadness that the family of Peter Green announce his death this weekend, peacefully in his sleep,” the statement reads.

The blues rock guitarist formed Fleetwood Mac with drummer Mick Fleetwood in 1967. A number of high-profile musicians who either knew or simply admired the famed blues guitarist reacted to his passing on Saturday.

Singer Yusuf Islam, who used to be known by the stage name Cat Stevens, remembered Green as “one of the unsung heroes of musical integrity, innovation and spirit.”

Musician Peter Frampton also took to Twitter to mourn the loss of Green Saturday afternoon.

“Most sadly have lost one of the most tasteful guitar players ever,” Frampton wrote. “I have always been a huge admirer of the great Peter Green may he rest in peace.”

English blues rock guitarist Bernie Marsden thanked Green for “everything” and said he had the pleasure of spending some time with Green over the last couple of years.

“He made me laugh, cry, wonder, and never failed to make me pinch myself when we were alone one to one. There I was, sat with my hero. As a musician I can only be one of the millions he touched, his talent for guitar playing, vocals and harmonica would have been more than most people could have possibly wished for, and then you add those wonderful songs, original, vibrant, atmospheric, outright psychedelic and so much fun, to listen to and witness,” Marsden wrote.

Marsden also tweeted a photo taken of Green at his house in February, the same day Fleetwood Mac performed a tribute to Green at the London Palladium. He recalled Green’s “cheeky mood” that day.

“When I asked if he would like to have been in London, he shrugged a little, gave me a smile and said, ‘No, I’m having a cup of tea with you.’ He made great tea,” Marsden concluded.

Black Sabbath co-founder Geezer Butler simply called Green “one of the greats,” calling his death “sad.”

Green, real name Peter Allen Greenbaum, was born on Oct. 29, 1946, in London. The gift of a cheap guitar put the 10-year-old Green on a musical path. He was barely out of his teens when he got his first big break in 1966, replacing Eric Clapton in John Mayall’s Bluesbreakers — initially for just a week in 1965 after Clapton abruptly took off for a Greek holiday. Clapton quit for good soon after and Green was in.

In the Bluesbreakers, he was reunited with Fleetwood, a former colleague in Peter B’s Looners. Mayall added bass player John McVie soon after. The three departed the following year, forming the core of the band initially billed as “Peter Green’s Fleetwood Mac featuring (guitarist) Jeremy Spencer.”

Fleetwood Mac made its debut at the British Blues and Jazz festival in the summer of 1967, which led to a recording contract, then its first album in February 1968. The album, which included “Long Grey Mare” and three other songs by Green, stayed on the British charts for 13 months.

The band’s early albums were heavy blues-rock affairs marked by Green’s fluid, evocative guitar style and gravelly vocals. Notable singles included “Oh Well” and the Latin-flavored “Black Magic Woman,” later a hit for Carlos Santana.

Green left the band in 1971. Even so, Mick Fleetwood said Green deserves the lion’s share of the credit for the band’s success.

Green was confined in a mental hospital in 1977 after an incident with his manager. He was released later in the year, and married Jane Samuels, a Canadian, in 1978. They had a daughter, Rosebud, and divorced the following year. Green also has a son, Liam Firlej.

Green returned to performing in the 1990s with the Peter Green Splinter Group. But in 1998, he made a rare appearance with Fleetwood Mac when the group was inducted into the Rock and Roll Hall of Fame.

Green, to some listeners, was the best of the British blues guitarists of the 1960s. B.B. King once said Green “has the sweetest tone I ever heard. He was the only one who gave me the cold sweats.”