Police have raided the Parramatta Mosque as part of their investigations into the fatal shooting of a police force employee on Friday.
Farhad Jabar Khali Mohammad, 15, shot and killed finance employee Curtis Cheng, outside NSW Police headquarters in Parramatta about 4.30pm on Friday.
Police have now raided the nearby mosque, which Farhad attend shortly before the shooting, the ABC reports.
The Parramatta Mosque, which is believed to have been raided overnight, is just a few blocks away from the site of the fatal shooting.
Police said the warrant was undertaken by arrangement with leadership at the mosque, who gave their full assistance to police.
Exclusive footage obtained by 7 News shows 15-year-old Farhad Jabar Khalil Mohammed walking along Church Steet, dressed in a black robe he changed into after praying at the mosque.
The video shows the radicalised teenager waving a gun and shouting at police, while young children played at the Good Start daycare centre just metres away.
Mr Cheng was shot at point blank range as he left work for the day, just as he had done for 17 years as a finance employee of the NSW Police Force.
According to witnesses the young gunman seemed joyous.
Senior police sources told 7 News the shooter managed to walk into the lobby of police headquarters unchallenged, picked his target inside, and followed Mr Cheng out before firing upon him.
Special constables tasked with protecting government buildings heard the shot and ran outside to confront the teenager, who was still firing shots.
The teenager of Iraqi-Kurdish background appears to have acted alone in shooting dead Mr Cheng, in what NSW Police Commissioner Andrew Scipione has confirmed as a terror-related attack.
At this early stage, Mr Scipione says investigators have no information to tie the boy to a specific group.
A senior police source told the ABC that it was Farhad's older brother who tipped off police about the 15-year-old's identity.
It is also understood Farhad's sister Shadi went missing on Thursday and flew out of Australia on a Singapore Airlines flight bound for Istanbul. It is believed that she may be attempting to reach Iraq or Syria.
Her family told police she had taken all her belongings.
Police have searched the teenager's North Parramatta home and confiscated computer equipment.
Earlier, Prime Minister Malcolm Turnbull called on Australia not to blame or vilify members of the country's Muslim community for the actions of a very small number of violent extremist individuals.
Mr Turnbull praised the actions of police who brought the situation under control quickly and express condolences to the family of Mr Cheng.
He said the incident had been "a shocking crime" and a case of "cold blooded murder", but said it would be counter-productive if people rushed to blame Muslim Australians.
New South Wales Police have sent condolences to the family of their 58-year-old colleague.
“Our condolences have been passed to Curtis’s family on behalf of all the NSW Police Force members," a police statement said.
"Officers from NSW Police Force have met and comforted members of the family during this tragic time.
“Curtis was admired and respected by his colleagues. He was a gentle man in every sense."
Mr Scipione and New South Wales Premier Mike Baird have expressed heartfelt condolences to the Cheng family.
“Our condolences have been passed to Curtis’ family on behalf of all the NSW Police Force members. Officers from NSW Police Force have met and comforted members of the family during this tragic time," Mr Scipione said.
“Curtis was admired and respected by his colleagues. He was a gentle man in every sense.
“What has occurred is shocking and it is a very sad time for those who worked closely with him and all our employees.”
The commissioner has also praised the officers who put their "lives on the line and acted incredibly courageous".
Mr Scipione has confirmed the motive of the gunman was political, and therefore linked to terrorism.
"We're a long way from establishing a full picture of this man, his exact motivations still remain a mystery to us," Mr Scipione said
"We are exploring every avenue with regard to why he did what he did."
Mr Baird described the events as "chilling".
"How can someone so young undertake such a chilling act ... we're all lost for words," Baird said.
"The shock of this event will be felt everywhere."
According to Fairfax, police sources confirmed the young teenage gunman "shouted religious slogans" before shooting the civilian police employee in the back of the head.
7 News understands the police HQ had received emails about a suspicious man taking photographs outside the building in the last two weeks.
'There was blood everywhere'
A witness to the fatal double shooting in Sydney's west has described hearing gun shots and seeing a man lying on the ground.
Real estate agent Edwin Almeida says he saw 15-year-old pacing and waving a gun outside the police centre in Charles Road on Friday afternoon.
"We looked out the window, saw security guards and what appeared to be a plain clothes police officer with gun drawn and pointing at the person that was now lying on the floor surrounded by a pool of blood."
He posted a video on his Facebook page of the area immediately after the shooting:
"Four five shots fired by man outside our office and in front of NSW police head quarters. Man shot down by guards and detectives."
"There was blood everywhere."
Mr Almeida said afterwards he could see two bodies under sheets lying in the street.
NSW Police have launched a critical incident investigation in the wake of the event.
Another witness told Seven News they heard "four shots fired first then there was a silence of about 10 to 15 seconds and there was another four shots".
"Initially I thought, there is construction going on here so I thought maybe noise coming from here so I just came down and somebody told me 2 people died," the witness said.