Jefferson Airplane guitarist Paul Kantner has sadly died. He was 74-years-old.

The musician passed away on Thursday, Jan. 28 from multiple organ failure and septic shock after suffering a heart attack earlier this week, his longtime rep Cynthia Bowman confirmed to the San Francisco Chronicle.

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Jefferson Airplane in 1970.

According to the California newspaper, Paul had been in poor health for many years leading up to his death. He had his first heart attack in March 2015 and suffered a cerebral hemorrhage in 1980.

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Paul co-founded the psychedelic rock band Jefferson Airplane with Marty Balin, Jack Casady, Spencer Dryden, Jorma Kaukonen and Grace Slick in 1965. He and Grace later formed a Jefferson Airplane spinoff group, Jefferson Starship, in 1974. The original Jefferson Airplane members were inducted into the Rock and Roll Hall of Fame in 1996 and were recently honored with the 2016 Grammy Lifetime Achievement Award.

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Paul in June 1973.

“Our condolences go out to the friends, family and fans of Paul Kantner of Jefferson Airplane on the news of his passing,” a message posted to the Doors’ Facebook page on Thursday read. “Music would not be the same without the sounds of the Doors and Jefferson Airplane, which both contributed so heavily to the signature sound of the sixties and seventies.”

Paul is survived by his three children: sons Gareth and Alexander and daughter China. Our thoughts are with the Kantner family during this difficult time.