A photo from NSW Police of the raids in Sydney Thursday morning. NSW Police Police have confirmed Australia’s largest ever counter-terrorism operation targeted a group planning “random acts of violence” against a member, or members of the public, on the streets of Sydney.

News agencies are reporting court documents, to be released later Thursday morning, are expected to reveal the terror group planned to behead a member of the public in Sydney, or potentially engage in a random mass shooting.

Australian Federal Police and intelligence officials launched the “largest counter-terrorism operation” in Australia across a number of suburban areas in Sydney and Brisbane Thursday morning.

Court documents expected to reveal the terror plan involved draping random Sydney person in Islamic State flag and beheading them on camera — ABC News (@abcnews) September 18, 2014

Authorities say behavior will be closely monitored on the streets of the NSW capital Thursday with police on alert for retaliation following the raids.

AFP Commissioner Andrew Colvin and NSW Police Commissioner Andrew Scipione addressed the media at a news conference in Sydney on Thursday morning and confirmed 25 warrants had been executed and 15 arrests made.

Colvin said the group was planning violent acts, particularly “random acts against members of the public” and that one person has been charged with terrorism-related offenses.

The individual was expected to appear in central court later Thursday, and Scipione said it would be "very apparent what was going to happen once the facts come out in the next couple of hours.”

“What we can indicate is the violence was to be perpetrated on a member of the public on the streets,” he added.

Of the 15 people apprehended, three were said to have resisted arrest. There were 800 police officers involved in the NSW operation alone, with at least one weapon seized and multiple properties and cars raided and searched.

Scipione said NSW Police would on Thursday implement Operation Hammerhead to deal with any “troublemakers” planning to “take retribution or create trauma within our communities.”

In the early hours of Thursday morning, Federal and State Police officers and officials from Australian security agency ASIO conducted raids throughout 12 Sydney suburbs.

The suburbs of Beecroft, Bellavista, Guildford, Merrylands, Northmead, Wentworthville, Marsfield, Westmead, Castle Hill, Revesby, Bass Hill, and Regents Park were targeted.

Three search warrants were also carried out in Brisbane’s south — in Upper Mount Gravatt East, Logan, and Underwood.

Police released video and photos showing heavily armed officers entering homes before dawn Thursday morning.

Monash University’s acting Director of the Centre for Islam and the Modern World Greg Barton told Business Insider after the federal government raised the terror threat to “high” on Friday the biggest question had been “what do authorities know about it and what are they doing about it.”

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