A family with two dogs was inside their house when it went up in flames, the ACT Emergency Services Agency says.
A house on Boyer Street in Casey caught fire at 2.48pm.
An Emergency Services ACT spokesperson said the top floor of the house was still engulfed in flames about 3.25pm.
The front double garage has collapsed.
The loungeroom and two bedrooms have also been affected by the fire.
The family rented the house.
One person was assessed for injuries, but no one has been taken to hospital.
ACT Fire and Rescue has not determined what caused the fire.
As of 4.20pm, thermal cameras were being used to ensure there were no remaining hotspots in the roof cavity.
More to come.
