Police Col. Jirapat Phothanaphan says the nationalities of the dead are not yet known, but that both Thais and foreign tourists are among 11 others who were injured.
Jirapat says the fire broke out about two hours before dawn Friday at the Tiger Disco in Phuket's popular Patong beach area.
He says the cause of the blaze is not yet known, but that authorities suspect heavy rains that led to sparks at a nearby electricity transformer may have triggered it.