Police say they are exploring all avenues surrounding the deaths of two children and two adults who were found in a home in Melbourne on Tuesday.

The bodies of a girl and boy, aged three and five, and two adults were found in the south-eastern suburbs home of Glen Waverley by police at 10:50am (AEST).

Police are hoping post-mortem examinations today will shed more light on the circumstances surrounding the deaths.

The children's parents are believed to be aged in their 30s.

An uncle who arrived at the scene said his family was devastated but believed their deaths may be accidental.

Abhay Singh believes the family may have died from an accident, possibly a leaking gas tank.

He says he first heard of the tragedy when his daughter rang him after seeing the news on ABC TV.

Mr Singh says the family was very happy but he could not explain why the children were not at school.

He said the last time he saw the family was last week, at an eight-year-old's birthday party.

"It's a mystery, there's no answer to it," he said.

The parents came to Australia from Fiji 15 years ago when they were single.

Both children were born in Australia.

'Just nasty'

Police interview neighbours near the house where four bodies were found. ( AAP: Julian Smith )

Police were called to the premises at Marcia Court after the alarm was raised by a member of the extended family.

Police say until autopsies are conducted they will not disclose the nature nor the circumstances of the deaths.

They say they are not looking for a suspect.

Detective Senior Sergeant David Snare says police have yet to determine when the family was last seen alive.

"It's a family unit, just nasty," he said.

"The homicide squad are involved because of the nature of the circumstances and the number of deaths."

Circumstances

Detective Snare refused to be drawn into the circumstances of the deaths.

When asked if it was a possible murder-suicide, he said police would not rule anything in or out.

"I'm not going to describe the interior of the house or the circumstances," he said

Neighbours describe the family as quiet and reserved.

Josh, who lives next door, says he did not know the family well but says everyone is shocked.

He says seeing the police cars was also very unsettling.

Another neighbour says it is very sad.

"Nothing like that happens around here, it's sad," he said.