Paul Kantner, the co-founder and guitarist for the influential band Jefferson Airplane, has died.

He was 74.

According to his publicist, Kantner died of multiple organ failure. He had a heart attack earlier this week.

Kantner helped found the psychedelic rock band Jefferson Airplane in 1965 alongside friend Marty Balin. Kantner wrote many of the band’s earlier hits, including “The Ballad of You and Me and Pooneil”, “Watch Her Ride”, and “Crown of Creation”.

In the early 1970s, after Jefferson Airplane had already amassed a load of fame, Kantner formed Jefferson Starship with a group of other musicians. When Airplane broke up, Starship continued on.

Kantner was romantically involved with Jefferson singer Grace Slick. They got together in 1969 and had a child, China. The couple broke up in 1975.

Paul Kantner, founding member and guitarist for Jefferson Airplane and Starship, has died https://t.co/TPZUsXBzcA pic.twitter.com/4xtVWU0iSf

— Rolling Stone (@RollingStone) January 29, 2016

Kantner was inducted into the Rock and Roll Hall of Fame in 1996.