Steely Dan guitarist and co-founder Walter Becker died Sunday (Sept. 3) at the age of 67.

News of Becker’s death was announced on his official website. Further details of his passing were not revealed.

Becker was absent at both of Steely Dan’s performances during July’s Classic West and Classic East concerts due to an unspecified illness. In August, Steely Dan’s Donald Fagen told Billboard that his bandmate was “recovering from a procedure,” but didn’t elaborate further.

After becoming musical collaborators as students at New York’s Bard College, Becker and Fagen went on to turn out numerous hit songs during the 1970s, including “Rikki Don’t Lose That Number,” “Deacon Blues,” “Kid Charlemagne,” “Hey Nineteen,” and “My Old School.”

The Grammy-winning band split up in 1981 but reformed in the 1990s, releasing a handful of successful albums.

Steely Dan was inducted into the Rock And Roll Hall Of Fame in 2001.

Shortly after Becker’s passing, Fagen shared a touching note about his longtime bandmate. Read his full statement below.

Walter Becker was my friend, my writing partner and my bandmate since we met as students at Bard College in 1967. We started writing nutty little tunes on an upright piano in a small sitting room in the lobby of Ward Manor, a mouldering old mansion on the Hudson River that the college used as a dorm.

We liked a lot of the same things: jazz (from the twenties through the mid-sixties), W.C. Fields, the Marx Brothers, science fiction, Nabokov, Kurt Vonnegut, Thomas Berger, and Robert Altman films come to mind. Also soul music and Chicago blues.

Walter had a very rough childhood — I’ll spare you the details. Luckily, he was smart as a whip, an excellent guitarist and a great songwriter. He was cynical about human nature, including his own, and hysterically funny. Like a lot of kids from fractured families, he had the knack of creative mimicry, reading people’s hidden psychology and transforming what he saw into bubbly, incisive art. He used to write letters (never meant to be sent) in my wife Libby’s singular voice that made the three of us collapse with laughter.

His habits got the best of him by the end of the seventies, and we lost touch for a while. In the eighties, when I was putting together the NY Rock And Soul Review with Libby, we hooked up again, revived the Steely Dan concept and developed another terrific band.

I intend to keep the music we created together alive as long as I can with the Steely Dan band.

rest in peace Walt. Hope there's a good guitar tech up there.

A post shared by @macdemarco on Sep 3, 2017 at 9:54am PDT

‪Walter Becker, you changed my life with your mystical music and guitar playing. You are so loved and I feel for your partner Donald Fagan and your fam. ‬ ‪Straight to the stars…. My friend. You were every one of them, shining bright in my soul Showing us all what was really possible. You are loved RIP

A post shared by Ryan Adams (@misterryanadams) on Sep 3, 2017 at 10:01am PDT

"…..still holds the crown baby" rip #WalterBecker possibly one of my favorite architects of the 70s "FM" smooth sound. Took it for granted growing up —before 10 I heard his music & Fagen's voice EVERYWHERE: supermarket, waiting rooms everywhere, cabs, offices, dentist chair, sporting events even (Sixers used to RUN "Peg" during Dr J's era) actually lol first time I got sent to principles office in 2nd grade was for "saying a bad word" (Hell, was a 4 letter word growing up & I didn't know who or what a "Peg" was but I knew someone in my class was going to 🎵"Helllllllllllllllllll"🎵 The first time we played w Michael McDonald a second after "man it's an honor" came "ok how long did Walt make you stack them vocals?" Walt was my first post "hey I dig these guys I wanna get em on a session" gig shortly after our Do you Want More album came out. I was all ready for him to make me do take after take after take like I heard he was notorious for—but uh shockingly he liked our loose playing and encouraged it. (Yeah I even tried to tune my drums Steely Dan low but he was like "I want you to sound like you, not like what we were doing way back then") This is a major loss man. An artist's artist. Someone who cared for the craft of music and pushing boundaries. They got a name for the winners in the world: his name is Becker

A post shared by Questlove Gomez (@questlove) on Sep 3, 2017 at 8:59am PDT

A definitive band of my childhood. My parents listened to Steely Dan non stop and I knew almost every word to every song by the time I was a teenager. They almost named me Aja and to this day I'm still pissed they didn't. My email address throughout my teens/early 20s was anymajordude@hotmail.com. One of my best memories is taking my dad to see them at the Greek in 2011. RIP Walter Becker 😔💔

A post shared by Best Coast (@best_coast) on Sep 3, 2017 at 10:12am PDT

#RIPWalterBecker Steely Dan is a huge part of my musical DNA

A post shared by Talib Kweli (@talibkweli) on Sep 3, 2017 at 10:03am PDT

Steely Dan changed the way I understand music forever; I started writing songs under the name "the Mountain Goats" the same month 1/2

— The Mountain Goats (@mountain_goats) September 3, 2017

that I bought "Katy Lied" on tape and started obsessing over it. Safe travels along the cosmos to Walter Becker: you changed my life. 2/2

— The Mountain Goats (@mountain_goats) September 3, 2017

I was once in a band that played only Steely Dan songs. It was hard and lots of fun. RIP Walter.

— Jason Isbell (@JasonIsbell) September 3, 2017

RIP Walter Becker. Half of one of the greatest and most original bands in rock history.

— Carl Newman (@ACNewman) September 3, 2017

This article originally appeared on Billboard.