March 9, 2016 7:41 AM EST

Paul McCartney, Ringo Starr and other musicians are mourning the loss of music producer George Martin, known for his work with the Beatles.

In a lengthy statement on his website, McCartney said Martin was “like a second father” who played an instrumental role in the band’s career. “From the day that he gave The Beatles our first recording contract, to the last time I saw him, he was the most generous, intelligent and musical person I’ve ever had the pleasure to know,” McCartney wrote.

Martin, who died at age 90, was sometimes referred to as the “Fifth Beatle” and produced much of the band’s material.

Below are some of the tributes that have pored in on social media:

Read more: Beatles Producer George Martin Dies Aged 90

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