Two police have been injured, one critically, and a man is feared dead after a six-hour siege ended in an explosion in western Victoria.
The blast occurred at a Derrinallum property early on Saturday after police spent several hours negotiating with a man wanted over a violent incident.
The blast, thought to have been caused by an explosive device, levelled the man's house and several outbuildings and was felt for several kilometres.
Police said two officers arrived at the property investigating a violent incident that had occurred earlier in the week.
They said the man became irrational and threatened self-harm.
Trained negotiators were called in but it's believed the man set off the device, injuring the two officers, who are from an un-named specialist unit.
One was flown to The Alfred hospital in Melbourne, where he is in a critical but stable condition with head injuries.
His colleague suffered cuts and bruises in the blast and is in a stable condition at Geelong Hospital.
"It was just a an enormous bang. It was just unbelievable. It shook the house," one resident said.
The man is missing and is thought to be dead but his fate will be unclear until the police bomb response unit declare the large property is free of explosive devices.
Superintendent Don Downes said homicide detectives and the professional standards command are investigating.
"We were all there to make an arrest and to try to resolve the matter peacefully. That was our aim," he said.
The nearby Hamilton Highway will remain closed until Monday at least.