LEIGH SALES, PRESENTER: Brutal gang warfare on the streets of Sydney has escalated with the shooting of a 13 year old girl at the front door of her home.

It's the latest attack in a new surge of violence that's included two men killed and four people injured in shootings in just the past week.

The girl shot last night was the sister of a member of notorious crime gang Brothers 4 Life which is being blamed for much of the violence.

The gang was founded in prison by convicted criminal Bassam Hamzy.

He's currently serving at least 36 years for murder and other crimes and authorities fear he's still controlling some of the violence from behind bars.

Sean Rubinsztein Dunlop has this report.

SEAN RUBINSZTEIN DUNLOP, REPORTER: Sydney's gang warfare has reached a terrible new low.

DAVID LAGATS, NSW POLICE: I think our greatest fears have now been reached with an innocent person. A 13 year old occupant inside the house was struck by the gunshot pellets and suffered wounds to her back.

SEAN RUBINSZTEIN DUNLOP: Late last night two men went to this house in Blacktown in Sydney's west. They asked for another man but his family shut the door on them. The men fired four shots hitting a teenage girl.

DAVID LAGATS: I think the public are over these shootings.

SEAN RUBINSZTEIN DUNLOP: By morning the crime scene was still under heavy police guard as neighbours struggled to make sense of the violence.

SENOVEVA SAME, NEIGHBOUR: We hear only just like one shot and we thought it was only nothing. Then we heard someone screaming so that's how we realised maybe something happened.

JANARDAN SAMI, NEIGHBOUR: Never heard anything like this. This is the first time we heard something like this. I got like four kids in my house here, you know all teenagers you know. I'm very scared to live here now, you know. This is my neighbour down here.

SEAN RUBINSZTEIN DUNLOP: This shooting was the latest in a new surge of gun violence which began a week ago at Revesby in Sydney's south west.

One man was killed, another seriously injured when a hail of gunfire was sprayed into a garage.

TOLEAFOA VELIA VELESI, NEIGHBOUR: And then all of a sudden I heard a man wailing sound, you know, crying out loud and then I knew this someone was shot.

SEAN RUBINSZTEIN DUNLOP: The dead man was Mahmoud Hamzy, a member of the family behind the notorious crime gang the Brothers 4 Life.

JAMAL RIFI, COMMUNITY LEADER: From all the information that I've been told he is a good guy. Being a cousin of the Hamzy does not make him criminal. He had a career in university and he was a university student. He comes from a good family, his parents are very well regarded, they live away from the area. He was visiting and he was at the wrong place at the wrong time. His killing is senseless killing, and I can feel for his parents.

SEAN RUBINSZTEIN DUNLOP: The morning after, there was nothing but bravado from the gang's self appointed leader at the scene.

GANG LEADER: A bit of fireworks went off. Someone got hit with a firework.

JOURNLAIST: Did you know the person who was shot?

GANG LEADER: No, I don't know. I don't know them, man.

JOURNALIST: Pretty serious fireworks, what does the number plate mean?

GANG LEADER: New Year's Eve came early.

SEAN RUBINSZTEIN DUNLOP: The number plates on the car, a clear sign of contempt for the police. MEOC, the acronym for the police Middle Eastern Organised Crime squad. The Brothers 4 Life are one of their key targets.

NICK KALDAS, DEP. COMMISSIONER NSW POLICE: Brothers 4 Life are very much a focus for NSW Police at the moment, and those who are involved in that group need to think long and hard about what they do over the next few days.

SEAN RUBINSZTEIN DUNLOP: The Brothers 4 Life gang was founded in jail by convicted murderer Bassam Hamzy, Australia's highest security prisoner. Even behind bars he's wielded enormous power using smuggled mobile phones to direct crimes. Police are investigating whether he played a role in the latest violence.

NICK KALDAS: Bassam hamcy's in custody. It's difficult how he could see how he played a role. Whether he had any influence on anyone is yet to be revealed. That's not certain yet.

JOURNALIST: How could he have any influence on people if he's locked up in the super max?

NICK KALDAS: If you're in custody you still talk to people, you're not isolated from the world. You may talk to people and ask them to do things for you. I'm not saying he's done it this occasion but it's a possibility and it's on the table.

SEAN RUBINSZTEIN DUNLOP: The Brothers 4 Life gang and the Hamzy family are under investigation for a series of murders, shootings, kneecappings and kidnappings in recent years. The gang has brought together criminals who have been linked to some of Sydney's most sinister crimes over more than a decade.

This recent attack in the car park of a Sydney sex club is an example of the kind of violence carried out by the Brothers 4 Life.

Two masked men ambush their victim, shooting him at close range.

The man was shot several times, remarkably he survived.

An associate of the gang has been charged with attempted murder.

JAMAL RIFI: Definitely they're dangerous but the sheer fact that action is dangerous, there is a lot of extortions, there's a lot of killing, now we have a dull moment and we will be quite happy but what happened recently in the escalation, we've seen people being shot at home in the safety of their home, 13 years old. That's terrible. Of course they are dangerous.

SEAN RUBINSZTEIN DUNLOP: All too often police investigating the gang and its crimes confront a wall of silence. Today the Premier reacted angrily after learning the parents of the girl shot last night were not helping investigators.

BARRY O'FARRELL, NSW PREMIER: And extraordinarily her parents are not cooperating with police. What sort of parent whose daughter has been injured in an attack like this will not cooperate with police? And that underscores, that underscores the problem that police across this state have.

SEAN RUBINSZTEIN DUNLOP: His comments have infuriated community leaders like Jamal Rifi who say the Government has failed to act on gang crime.

JAMAL RIFI: It was appalling what the Premier's remarks after 18 months of silence, all what he could do was to come up to blame the parents of innocent victim and he's questioning why they're not cooperating with the police? It's too simple. They are afraid.

SEAN RUBINSZTEIN DUNLOP: Later today the Premier released a statement saying the family is now cooperating with police but the community is still living in fear.

KEVSAR TRAD, ISLAMIC FRIENDSHIP ASSN. OF AUST: People are afraid that some of their children might be drawn into that lifestyle. People are afraid for the safety of their children. People are afraid for the safety of their environment. They know that these boys who are out there who may be attracted to this lifestyle.

SEAN RUBINSZTEIN DUNLOP: Police say they need the community's support.

SUPT GAVIN DENGATE, NSW POLICE: I know the families do know what's going on. I talk to them, generally a number of them are scared in the discussions I've had with them. But we will keep going back and back and back and we won't stop doing it.

SEAN RUBINSZTEIN DUNLOP: Scenes like this have become all too familiar for the community that's being wracked by this violence. On Friday hundreds gathered to farewell Mahmoud Hamzy, the man shot dead last week in the garage of his cousin's home. After today's shooting more revenge attacks are feared.

JAMAL RIFI: The community feel they're living in the war zone. The fear is palpable. We are all concerned. Instead of taking our young people to their wedding ceremony. We are walking into their funeral processions and there is a lot of fear, I can tell you.