Police have confirmed an 11-year-old boy and his mother died during a Southland house fire on Thursday.

The house was ablaze early in the morning in View Street, Manapouri.

Detective Sergeant Mark McCloy said on Friday a couple and a child were living in the rental house, but the man was away working when the fire took hold.

He said police were satisfied no one else was in the property at the time.

McCloy said the house had been decimated, and they had to use a crane to remove what was left of the roof to allow the scene to be examined.

Emergency service were called to the house shortly after 3.30am.

One person was confirmed dead on Thursday, with the others at the time unaccounted for.

The cause of the blaze remains unexplained.

A methodical search is being done by a specialist team.

Main image (RNZ/Southland App): Fire crews responded to the fire at a single-storey house in Manapouri about 3.30am on Thursday.