Police are investigating the "unusual" death of four people found by a relative at a home in Melbourne's north.
Detective inspector Dean Thomas said police were called to the Broadmeadows home around 2am on Tuesday.
On arrival, they found the bodies of a 17-year-old boy, two men, aged 32 and 37, and a 42-year-old woman.
"We certainly don't know what has caused their death ... it's not obvious to us at this time," Thomas told reporters at the scene.
"It may be from a drug overdose, it may not.
"It's unusual that we find four people deceased in the one property potentially from a drug overdose but we've got to keep an open mind until we can confirm that's the case," he said.
The bodies were found in the same area of the house, leading police to believe they were sitting together, and there was no evidence to suggest there had been any violence inside the home.
Police believe one of the victims lived at the home and three others were visiting.
Their bodies are yet to be formally identified.
The bodies were discovered by a man, who claims to be a relative of at least one of the deceased, at the home in Broadmeadows.
The man, named as Corey by Nine News and described as a family member and a neighbour, said he went to the home and knocked on the door but no-one answered.
He says he looked through a window and saw a 17-year-old boy lying on the floor.
"I've come home to find family members in the house deceased and it just tortured me, shocked me," he told Nine's Today program.
"I think (it was) an overdose but I'm not too sure exactly."
Corey was later joined at the scene by several distressed people believed to be family members and friends.
One man tried to enter the scene but was stopped by officers.
Relatives were later escorted inside the home by police.
