Yes bassist and co-founder Chris Squire died Sunday at the age of 67.

“Utterly devastated beyond words to have to report the sad news of the passing of my dear friend, bandmate and inspiration,” Yes’ keyboard player Geoffrey Downes tweeted.

According to a statement from the band, Squire died peacefully in Phoenix, AZ.

Squire had revealed back in May that he was fighting acute erythroid leukemia.

Yes will kick off a co-headlining tour with Toto on August 7.