LOS ANGELES —Keith Emerson, founder and keyboardist of the progressive-rock band Emerson, Lake and Palmer, has died. He was 71.

Emerson’s longtime partner, Mari Kawaguchi, called police to his condominium in Santa Monica, California, at about 1:30 a.m. Friday.

Emerson had an apparent self-inflicted gunshot wound to the head, and authorities are investigating his death as a possible suicide.

Kawaguchi told police that Emerson could have died anywhere between Thursday evening and Friday morning.

Emerson, drummer Carl Palmer and vocalist/guitarist Greg Lake were giants of progressive rock in the 1970s, recording six platinum-selling albums. They and other hit groups such as Pink Floyd, the Moody Blues and Genesis stepped away from rock’s emphasis on short songs with dance beats, instead creating albums with ornate pieces full of complicated rhythms, intricate chords and time signature changes. The orchestrations drew on classical and jazz styles and sometimes wedded traditional rock instruments with full orchestras.

Emerson, Lake and Palmer’s 1973 album “Brain Salad Surgery” included a nearly 30-minute composition called “Karn Evil 9” that featured a Moog synthesizer and the eerie, carnival-like lyric: “Welcome back my friends, to the show that never ends.”