The bodies of a seven-member family were found in a flat in the Strand on Tuesday, Cape Town police said.

"It's bizarre what happened," Inspector Olebogeng Tawana said.

"The family had locked all the windows and doors in the flat, and started an inside fire with charcoal. We don't know why they did this because it was not cold or raining."

Police suspect the family ? three adults aged 48, 47 and 41, as well as four children aged seven, nine, 10 and 16 ? died of smoke inhalation.

ER24 paramedics spokesperson Tristan Wadeley said an eighth person, a woman in her twenties, survived and was taken to a local hospital in a critical condition.

The employer of one of the family members arrived at the Terrace Acres flat on Tuesday, found the door locked and alerted the flat agent.

Tawana said: "The agent opened the door after midday and found the bodies."

Police were not sure how long the bodies had been there, but presumed the incident occurred on Monday. An inquest docket has been opened and post mortems would be carried out shortly.