An alleged Sydney terror plot to target a passenger jet came undone following a vital tip-off from British intelligence, who alerted Australian law enforcement last Monday.
Four men were immediately put under 24-hour surveillance.
The men who are under investigation have been named as Mahmoud Khayat, Khaled Khayat, Khaled Merhi and Abdul Merhi.
Each man is entitled to be considered innocent. They may not be charged.
Police have seized airline documentation from a raided house as well as a meat grinder - allegedly to be used as part of bomb intended to disperse poisonous gas.
Neighbours expressed disbelief as new pictures emerged of the arrest of Mahmoud Khayat in Lakemba.
"For us it's a good family," one neighbour said. "Good person, good everything."
Police are working hard to discover why intelligence out of the Middle East allegedly implicates Mahmoud Khayat in a conspiracy and are continuing to search his apartment complex thoroughly.
"Those search warrants will probably last a few days," Federal Police Commissioner Andrew Colvin said.
"We have people who are being interviewed and no-one has yet been charged."
Also being questioned in Khaled Merhi, seen bandaged and bleeding outside his Surry Hills terrace on Saturday night.
"I can understand people are very hungry for details but because of the nature of this investigation, and the fact that it is ongoing, I'm just not in a position to confirm anything," Justice Minister Michael Keenan said.
Standard items such as smart phones, an iPad, SIM cards and cars were seized at raided properties over the weekend.
At Lakemba, documentation for a Jakarta-to-Sydney flight route was found in the garbage.
Police also seized a note linked to the home raided in Surry Hills, where components of a meat grinder and "multi-mincer" were found.
Investigators are examining whether a mincer was to be potentially used as a bomb designed to disperse poisonous gas mid-flight.
"The security threat to our nation is as prevalent as it's ever been," Border Protection minister Peter Dutton said.
Prime Minister Malcolm Turnbull was alerted to the alleged plot on Wednesday by British intelligence and the following day security measures at Sydney Airport were fortified.
- Police conduct terror raids across Sydney
- Alleged terror plotters 'planned to bring down flight'
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On Saturday, when circumstances favoured Joint Counter-Terrorism teams, they carried out their raids as security at all of Australia's major airports was increased.