The fire broke out in Mahim's Nayanagar slum early today, fire brigade sources said, adding that the cause of the fire was not yet known.
Eight fire engines and two ambulances were rushed to the spot, they said.
Asked to comment on reports that the dead included a woman and three children, a spokesperson for the BMC's disaster control room said the bodies were awaiting identification.
Five bodies are at the Bhabha Hospital and the sixth is at the Sion Hospital.
The injured have also been shifted to the Bhabha Hospital, the spokesperson said.
