A woman's body has been found in a fire-ravaged home after firefighters rescued two children from the blaze.
Emergency services were called to the Perth residence in the southeastern suburb of Roleystone about 2am on Tuesday.
The children escaped the fire unharmed but a woman remained missing.
Her body was later found inside the burnt-out home.
Premier Roger Cook said it was a "desperately sad situation".
"Our hearts go out to everyone impacted by that event," he told reporters.
"We're obviously deeply relieved that the kids were able to be rescued ... but for someone to lose their life and to lose their life under such circumstances is incredibly saddening."
Arson Squad detectives remain at the scene and the cause of the fire has not been determined.