Family bludgeoned in Sydney home

According to NSW police, the five victims were killed with a blunt weapon. Photo / Getty Images

Five members of the same Sydney family were killed with a blunt weapon in an "extraordinary" and "extremely violent" targeted attack in the city's northwest, police say.

A female relative found four of the five bodies, including two children, upstairs in the family's home on Boundary Rd, Epping, on Saturday morning.

Detectives say they had been killed between midnight and 9.50am.

The victims were Chinese-born Min Lin, 46, his wife, Yun Li Lin, two sons aged 12 and 9 and another female relative aged in her 40s, the Sydney Morning Herald reported.

Detectives initially believed they were dealing with a domestic incident, after finding the bodies of Mrs Lin, the second woman and the two boys.

But when Mr Lin's body was found in a bedroom with serious head injuries, they realised they were dealing with the murders of five people, the SMH said.

NSW homicide commander Geoff Beresford said it was unlikely the killings were robbery-related as nothing appeared to have been stolen from the home.

"At this stage of the inquiry it's too early to rule it out," Mr Beresford said yesterday.

No suspects had been identified as "persons of interest", he said, but investigators were "very open-minded of motive".

"What we can rule out at this point is that there are certainly not gunshot wounds," Mr Beresford said.

"We don't believe a firearm was involved.

"We don't believe that stabbing was the cause of death.

"It certainly appears that all the injuries were blunt-force trauma to the upper bodies and to the heads of the victims."

In late May, Mr Lin witnessed an armed robbery near his news agency at the Epping Shopping Centre.

Police say they are not sure if there is a connection between that and his murder.

The SMH reported that detectives were also investigating whether the family had been the target of extortion demands.

The family are understood to have owned the news agency for five years.

Police spent the weekend speaking to members of the Chinese community and relatives of the victims, including the Lins' daughter, who is returning to Sydney.

Mr Beresford described the murders as "a terrible tragedy".

"It is extraordinary, it's extremely violent and certainly unusual in my experience to have this many people murdered on one occasion."

However, he did not believe there was any reason for concern among neighbours of the family.

"We're open-minded but we believe it was quite targeted," Mr Beresford. " I don't believe there's any reason for undue concern at this point in time."

- AAP