Australian police arrested five people in raids on several homes in Sydney on Wednesday in their investigation of the murder last week of a police accountant that they said was "linked to terrorism".
New South Wales police said the boys and men, aged from 16 to 24, were taken into custody for questioning over the shooting of Curtis Cheng as he left police headquarters in Parramatta on Friday.
The gunman, Farhad Khalil Mohammad Jabar, 15, was shot and killed by police at the scene. He was identified as coming from an Iraqi-Kurdish background and having been born in Iran.
New South Wales Police Commissioner Andrew Scipione said on Saturday they believed Jabar was "politically motivated and therefore linked to terrorism."
More than 200 police took part in dawn raids on four houses, the biggest anti-terrorism swoop since the so-called Operation Appleby a year ago that targeted some of the same streets and detained 17 people.
On Tuesday, police arrested a 17-year-old boy on his way to the same school were Jabar was a pupil, charging him with offences related to the use of social media to harass and intimidate. The boy, whose identity was withheld, was also charged with assaulting and intimidating police.
The murder of Cheng by Jabar has raised questions about the Australian government's focus on national security and the "war on terror" rather than social cohesion and inclusion.
Some experts say that strategy has helped create an environment for radicalised Muslim youth to emerge in disproportionate numbers. A staunch ally of the United States and its battle against Islamic militants in Iraq and Syria, Australia has been on heightened alert for attacks by home-grown radicals since last year.
