Two police officers who were shot dead while on duty in a rural Australian town have been named, as a massive search continues for their alleged killer.

Victoria Police identified the victims as 59-year-old Detective Neal Thompson - a local officer on the brink of retirement - and 35-year-old Senior Constable Vadim De Waart.

The pair had travelled to the property in Porepunkah, north-east of Melbourne, alongside eight colleagues to execute a warrant for alleged sexual offences. Another officer was seriously injured in the shootout but is recovering after surgery.

Police say the suspect - named as local man Dezi Freeman, 56 - is heavily armed and still at large more than 24 hours on.

Thompson joined the force in 1987 and worked with the major fraud and crime squads before moving to the town of Wangaratta - an hour from Porepunkah - in 2007. A great lover of the outdoors, he was planning for his imminent retirement.

De Waart was temporarily posted to Wangarratta, but lived in Melbourne, where the avid traveller had moved from Belgium.

In a statement, Victoria Police Chief Commissioner Mike Bush said the devastating loss of the two officers struck at the heart of both the broader policing family and the Porepunkah community.

Police have said it is too early to answer questions about Mr. Freeman's beliefs - but the incident has revived questions over how authorities deal with extremist views. The manhunt continues, with residents in the area urged to stay vigilant as the search operations intensify.