Emergency services were called to the house on Wagensveldt St, Kingston, around midnight to find it well alight.
The fire was undercontrol by 2.51am. Two cars outside the house were also alight when firefighters arrived and several neighbouring houses at risk of also catching ablaze were saved.
Thirteen people have been confirmed as residents of the house and only two escaped, with eleven still missing, a Department of Community Safety spokeswoman said.
Two men escaped the blaze and suffered minor injuries attempting to extinguish the fire.
It is thought that at least two families were living in the house at the time of the fire.
The disaster victim identification squad and specialist forensic officers will assist with investigations.