Mosque raided after Australia 'terrorism-linked' shooting

Sydney: An Australian mosque reportedly visited by a 15-year-old boy before he shot dead a civilian police employee in an "act of terrorism" has been raided, police said today, as authorities boosted efforts to tackle youth radicalisation.

New South Wales state police said the mosque in Parramatta in western Sydney -- close to the scene of the double shooting on Friday afternoon -- was raided with the consent of religious leaders.

"NSW Police yesterday executed a warrant at a mosque in Parramatta," police said in a statement.

"The warrant was undertaken by arrangement with leadership at the mosque who provided full assistance to police at all times."

The 15-year-old gunman, who killed finance worker Curtis Cheng at close range outside the police force's headquarters before he was shot dead by officers, visited the mosque before the shooting, according to the Australian Broadcasting Corporation (ABC).

Prime Minister Malcolm Turnbull said the attack "appears to have been an act of terrorism".

Police would not provide further details about the raid, while senior sources told the ABC that the teen's sister went missing Thursday and boarded a Singapore Airlines flight to Istanbul, adding that she could be bound for Iraq or Syria.

Foreign Minister Julie Bishop would not comment on the report of the girl's travels, but said Australian federal and state governments were in talks with Muslim communities after the boy was identified as being of Iraqi-Kurdish background and born in Iran.

"Yesterday, Prime Minister Turnbull and (NSW) Premier Mike Baird had a long conversation with not only... Relevant agencies but also leaders in the Muslim community," Bishop told the ABC.

"We're certainly reaching out to the leaders of the Muslim community but working with the families at a grassroots local level.

"It's the families that will be our frontline of defence against radicalised young people."

Investigators have yet to establish why the teen -- who has no criminal history -- targeted Cheng, a 58-year-old father of two.

NSW Police Commissioner Andrew Scipione described Cheng, who had worked for the force for 17 years, as "admired and respected by his colleagues".

"He was a gentle man in every sense."