A woman has been detained by police after a tense stand-off with heavily-armed STAR Group officers south of Adelaide.

They were called to the Seaford Meadows property following a house fire at about 8.30am and found the woman naked and brandishing a knife.

STAR Group officers moved in used a baton to knock the weapon from her hand.

The woman has been detained under the Mental Health Act and taken to the Flinders Medical Centre for treatment.