A pet deer has attacked and killed a man and seriously injured his wife in Victoria's north-east.

Key points: The man died from his injuries shortly after the attack

The man died from his injuries shortly after the attack The woman was flown to Melbourne with serious upper body and leg injuries

The woman was flown to Melbourne with serious upper body and leg injuries Police killed the pet stag at the scene

Paul McDonald, 47, had gone out to feed the animal on the property at Moyhu, south of Wangaratta, when the deer attacked him about 8:20am.

His wife, Mandi McDonald, was then attacked when she tried to help her husband.

The ABC has been told the couple's teenage son hit the deer with a lump of wood to save his mother.

The couple suffered critical injuries and Mr McDonald died a short time later.

His wife was airlifted to the Alfred Hospital in Melbourne where she was in a critical condition on Wednesday night.

Ambulance Victoria said she had suffered upper body and leg injuries.

The deer was killed by police. ( Facebook )

'Very traumatised'

Acting Senior Sergeant Paul Pursell described it as an "absolute tragedy".

He said a local ambulance officer treated the couple at the scene but the man's injuries were fatal.

He said the family was "very traumatised".

"The family are just devastated. There is a large family network and the [people] we've spoken to… it's beyond words how affected they are by this incident."

The couple's son and daughter have travelled to Melbourne to be with their mother in hospital.

"Moyhu is a small community … the people who are involved in the incident are well known to them, so what we're looking at putting in place are some opportunities for counselling for community members," Acting Senior Sergeant Pursell said.

He said the deer was a cross between a red deer and an elk, known as a wapiti.

The family had kept the stag for six years and it was the only deer living on the property, along with a small number of sheep.

Local resident Patrice Larkin said she knew the couple well.

"They'd come in the shop every second or third day. We had the Moyhu general store for 12-and-a-half years," she said.

"When we heard, you just can't believe it. A deer. Their pet deer. You just can't believe it."

Describing Mr McDonald, she said: "He's a bit of a character, you could have a good laugh with him, a bit of fun.

"I can't even imagine when this all sinks in … we just happened to be behind the property near them and it was six ambulances, a helicopter, police. We didn't know what was happening."

The family had kept the stag at their Moyhu property for six years. ( ABC News: Ashlee Aldridge )

Steve Garlick, the chairman of the deer management committee at the Australian Deer Association, said it was very unusual for a deer to kill a person.

"Deer are much less likely to attack anyone than they are to run away from them," he said.

"The majority of encounters most people will have with deer is with deer fleeing in the opposite direction."

Police officers shot and killed the stag at the scene due to "concerns for the paramedic's safety on scene".

Police will prepare a report for the coroner.