Police believe the more than 7000 hectare blaze that destroyed three homes and killed almost 1000 stock at Barnawartha was caused by a tree falling on a power line in strong winds.
Police, working with CFA investigators, say the a limb of a gum tree fell onto power lines on a Riley's Road property.
The powerline is run by AusNet Services, previously known as SP AusNet. The company was involved in one of the country's biggest class actions, having paid out $494 million last December to the victims of the deadly Black Saturday bushfire.
Wodonga detectives located the ignition point on Sunday and returned with CFA fire investigators Monday morning.
Acting Inspector Kevin Coughlan said police would gather evidence from the landowners and neighbours.
"We believe a tree has come into contact with power lines and with that contact has caused the Barnawartha fire," he said.
"We're certainly not laying any blame with that."
A spokesman for Ausnet said it was "pure speculation" for anyone to confirm a cause.
"Our primary goal is to get customers back on supply," he said.
He said about two dozen homes in the Indigo Valley were out of power.
A representative for the company at a community meeting told residents they could be without power for another two days while personnel try to get into the fire ground.
The meeting also heard concerns from residents about the Valley's lack of mobile coverage, an ongoing problem for residents who have said it is a fire hazard.