Manhunt for alleged cop killer enters third day

A manhunt for a heavily armed accused police killer is entering its third day, with wintry conditions complicating search efforts.

Detective Leading Senior Constable Neal Thompson, 59, and Senior Constable Vadim De Waart, 35, were shot dead while attempting to serve a search warrant at a Porepunkah property on Tuesday.

Another wounded officer is expected to recover after undergoing surgery.

The accused gunman Dezi Freeman - also known as Desmond Filby - fled into bushland, plunging the town of about 1000 residents in Victoria's high country into lockdown.

Porepunkah Primary School reopened to students on Thursday after it went into lockdown following the shooting.

However, police reiterated warnings for community members to stay indoors as they battle the elements in the hunt for the accused gunman.

The township in the state's northeast is 280m above sea level and close to Mount Buffalo, where several centimetres of snow fell on Wednesday.

Snow is forecast to fall above 900m in the area on Thursday, with maximum day-time temperatures tipped to hover between 5C and 13C.

Meteorologist Helen Reid said snow down could fall to 600m in Victoria as a cold snap descends on parts of SA, Tasmania, Victoria and NSW from Friday.

"Higher parts of the mountains, especially near the Victorian-NSW border, could get half a metre of snow during this outbreak," she said.

Overnight, Melbourne's iconic landmarks were lit up in blue to honour the dead officers.

Flinders Street Station, the Shrine of Remembrance and Parliament House were among the buildings bathed in blue.

Flags remained at half-mast at government buildings on Thursday.

Victorian Police Minister Anthony Carbines said he was confident police had the situation in hand as the major air and land search rolls on in severe weather.

"It's a complex operation and they're throwing everything at it," he told ABC Radio on Thursday.

Community members have paid their respects at the nearby Wangaratta police station, where the foyer is laden with colourful bouquets of flowers in memory of the fallen officer.

Premier Jacinta Allan expressed her deepest sympathies to the family, friends and colleagues of the two officers.

"It's a very physical way that we can say to the men and women of Victoria Police, we stand with you, we support you, we care for you, we love you, particularly in this time of grief," she said.

"We continue to provide every support necessary to the work of Victoria Police as they deal with this individual who perpetrated this most evil and awful of criminal acts."

The 56-year-old suspect, who has bush survival experience, was last seen wearing dark green tracksuit pants, a dark green rain jacket, brown Blundstone boots and reading glasses, police said.

He is believed to be a sovereign citizen, an ideology that questions government authority and whose followers believe the rule of law doesn't apply to them, and who disassociate from society.