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A seven-hour siege has ended with the discovery of a woman's body and the arrest of a man in the Victorian city of Geelong.
It ended when the man set the Norlane house alight tonight, with police storming into the home while firefighters doused the fire from outside.
Police discovered the woman's body in a front room and arrested the man, who had injuries from the fire.
Police said they were called to the house in Rose Avenue around 12pm (2pm NZ time) today after a 42-year-old man called relatives this morning to say he was at home armed with a firearm and had killed his de facto partner.
He barricaded himself inside the house threatening to harm police and himself, while officers from the Special Operations Group attempted to negotiate with him throughout the afternoon.
The body of a woman, believed to have been aged in her 40s, was later found in a front room of the house.
Police had earlier been unable to confirm that the man had a woman in the house with him.
Police said the man started a fire in the front of the home just after 7pm, using an accelerant he had sprayed around the house earlier in the day.
Police surged into the house while Country Fire Authority (CFA) firefighters doused the fierce fire from outside and extinguished the flames.
"He had threatened to damage the house earlier," police spokeswoman Sergeant Creina O'Grady said.
"The fire in the front room erupted in flames.
"The CFA quickly extinguished them."
The man, from Norlane, was taken to hospital under police guard and is being treated for injuries sustained in the fire.
Police will question him once treatment is complete and he is fit for interview.
The cause of the woman's death is unknown at this stage, police said.
Homicide detectives are waiting for crime scene personnel and a pathologist to examine the scene.
Residents evacuated from neighbouring houses in Rose Avenue have now been allowed to return to their homes and the road is open to traffic in both directions, Sgt O'Grady said.
- AAP