Keith Emerson, the legendary keyboard player in Emerson, Lake and Palmer (ELP), died Thursday night at the age of 71.
Police said late Friday that the death is being investigated as a suicide, the AP reported.
"Keith was a gentle soul whose love for music and passion for his performance as a keyboard player will remain unmatched for many years to come," Palmer wrote. "He was a pioneer and an innovator whose musical genius touched all of us in the worlds of rock, classical and jazz. I will always remember his warm smile, good sense of humor, compelling showmanship, and dedication to his musical craft. I am very lucky to have known him and to have made the music we did, together. Rest in peace, Keith."
The band's official Facebook page confirmed the news shortly after Palmer's post, saying only that he died at his home in California and asking readers to respect the family's privacy.
The Rolling Stone called Emerson "one of the greatest keyboardists of his generation," beginning as a member of the band The Nice, then founding ELP in 1970 along with guitarist Greg Lake and drummer Carl Palmer.
In a condolence posted on Twitter shortly after the announcement, Mike Portnoy, a drummer in the progressive "prog" rock community, lamented the passing of the "Jimi Hendrix of keyboards," and one of the pioneers of the prog rock sound.
Emerson was scheduled to go on tour in Japan next month.
This article has been updated to reflect that the death is being investigated as a suicide.