A house has burnt down in Manapouri overnight (4 Jul).

It's unknown how many people were at the address when the fire started, however Police and Fire and Emergency Services (FENZ) are working to account for them.

The fire service was alerted to the house fire at 3.35am and responded with two engines from Te Anau and one from Manapouri.

The single storey 8m x10m dwelling in View Street was well involved when crews arrived.

Southland Police area commander Inspector Mike Bowman said the cause of the blaze was unexplained and police, including CIB, continue to have a presence at the scene.

One fire crew has also remained onsite.

Inspector Bowman said further details would be provided when they became available.