Phil Lesh, founding bassist for the Grateful Dead, died Friday morning at 84, according to a post on his official Instagram account.

The cause of his death was not immediately clear.

Lesh, along with Jerry Garcia, Bob Weir, Ron McKernan and Bill Kreutzmann, formed the Grateful Dead in Palo Alto in 1965, and the band had a devoted following known as "Deadheads."

In addition to playing bass, Lesh also sang high harmonies for the band and provided the occasional lead vocal, according to the New York Times. He also co-wrote some of the band’s most noteworthy songs, including "St. Stephen," "Dark Star," "Cumberland Blues," "Truckin'" and "Box of Rain," the Times reported.

The Instagram post Friday morning read as follows: "Phil Lesh, bassist and founding member of The Grateful Dead, passe

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