Greek pop star Giorgos Mazonakis, who also enjoyed a strong following among the Greek diaspora, has died of a heart attack after being rushed to a hospital in Athens. He was 54.

Mazonakis reportedly suffered cardiac arrest on Friday afternoon while at a clinic in Kolonaki for scheduled therapy.

Later on Friday, the doctor monitoring the singer was summoned to provide a statement to police about the events leading up to the cardiac arrest.

Police are working to establish the timeline from the moment Mazonakis arrived at the clinic to the onset of his severe discomfort and the subsequent call to the ambulance service.

Doctors at Athens’ Elpis Hospital attempted to resuscitate the singer, but he was pronounced dead less than an hour after being admitted.