Joe Antoun, 50, was shot four to five times at close range when he answered the door of his house in Jersey Road, Strathfield, about 9.35pm on Monday.

Paramedics tried to revive Mr Antoun but he died at the scene.

His wife, Tegan, and their twin six-year-old daughters were at home.

The children reportedly witnessed the shooting and were outside the house in their pyjamas as ambulances arrived.

Nemer Antoun, 53, said his brother's death had destroyed his family and begged the perpetrators to give themselves up.

"Hand yourself in, guys. I certainly wish that maybe you can confront your demons," Mr Nemer said.

Joe Antoun, who had links to the construction industry, was a "gentle man", who "helped more than he hurts", his brother said.

Nemer Antoun said Joe was a loving father and wanted to raise his daughters in a safe, beautiful country.

“[The way he died] was barbaric. No one deserves to die that way. Not only did they destroy one family, they destroyed a few families by doing this. They are a bunch of cowards.

"All I can say is that the guy is not a criminal, he had done what he wanted to do in life."

Police are now looking for a man, possibly wearing a hooded jumper, who was seen leaving the area moments after the victim was shot.

Inspector Craig Miller said police believed the attack was targeted but would not speculate on whether bikies or drugs were involved.

"For any area, any of these incidents are very disturbing and alarming," Inspector Miller said.

"It appears the shooting has been targeted. However, it's too early in the investigation to elaborate any further at this time."

Homicide Squad detectives and Burwood police spent much of the night collecting forensic evidence from the house and doorknocking neighbours.

The shooting occurred less than 50 metres from an aged-care home, and police were only allowing workers and residents into the street.

Santa Sabina College campus is in the street behind where the shooting occurred and contract workers doing maintenance on the school grounds were not allowed to drive in with their tools and equipment.

A Jersey Road resident who lived a few doors up from the crime scene said he thought he heard three shots fired about 9.30pm.

"It was like fireworks, like 'bam bam bam'," he said.

The resident said he was surprised there had been a shooting so close to his home, describing the area as "quiet".

One resident, who asked not to be named, said the family had moved in only recently.

"They keep to themselves," she said. "I don't think the dad worked."

Another resident, Sean Eoloy, said he was shocked the crime happened in Strathfield.