A mother and her three young children have been found dead at a home in Melbourne's north-west this afternoon, with police and neighbours rocked by the "tragic" incident.

Police arrived at the Tullamarine property about 12.20pm today to find a 42-year-old woman, two young girls aged seven and five, and a three-year-old-boy dead at the home.

Acting Deputy Commissioner Robert Hill said when police arrived at the Burgess Street home they were greeted by ambulance members in the front yard with a 48-year-old male in their company, who was confirmed to be the children's father and the husband of the woman.

"I'm devastated, it's so close to home … these are people who've spent time in my home … my kids love their kids," a neighbour Marie Groves told 9News.

"She was the best mum, those kids were beautiful … how am I gonna tell my kids?" Ms Groves said.

Deputy Commissioner Hill said the incident would have a huge impact on the community and police at the scene.

"This is a tragic event, the loss of life tragic in any circumstance but when it involves children, it's even more heart-wrenching."

"These people died in suspicious circumstances."

Acting Assistant Commissioner Mark Galliott said officers investigating the incident would receive a wealth of support given the traumatic circumstances.

"This will have long-lasting effects on the police that have attended, on extended family, the community, the neighbourhood, the emergency services, and everybody else involved.

"They'll be lifelong memories that they'll have to deal with … so we will make sure that the welfare of our members and the emergency services that attended are paramount.

A crime scene has been set up and the Homicide Squad is present and overseeing the investigation.

Police are not looking for anybody else in relation to the deaths and the family's next of kin has been notified.

"We have one male who's assisting us with our inquiries and assisting us alone," Deputy Commissioner Hill said.

"There was no other party … there is no other party that we seek at this point in time.

"But we should not draw conclusions that that male may be culpable for this offending. We are well and truly – we've got a long way to go before we can understand and appreciate exactly what occurred.

"I just want to make it very clear that we're not – and should not – be drawing any conclusions at this point in time as to what occurred. We simply don't know."

Deputy Commissioner Hill said there is no history of family violence associated with the family and several avenues of inquiry were being investigated, including the possibility of murder-suicide.

Outside the home more locals expressed their shock at the tragic circumstances.

"They're a beautiful family, they're just a beautiful family," one man said.

"It is sad, very sad to hear people have died around here in Tullamarine," John Ozolins told 9News.

"We don't have any trouble here at all."

Neighbours said the area was peaceful and the situation was a shocking one.

"I'm in shock, I'm shaking," they said.

"It's a very quiet street, very quiet … there's been no problems anywhere."

Neighbour John said the mother-of-three was a kind person and the three siblings lovely.

"The kids were always dressed nice, she was always polite, she'd say hello … really friendly."

The 48-year-old husband and father was treated by paramedics at the scene and is in the custody of police.

Detectives are considering him a person of interest and he will be formally interviewed.

Readers seeking support can contact Lifeline on 13 11 14 or Beyond Blue on 1300 22 4636.