Officers wearing hazardous material or bomb disposal suits walked inside the property in Greenvale. Credit:Eddie Jim Police late on Friday set up a large, bright lights at the corner of Clare Boulevard and Helmsdale Crescent. A family living close to the raided house was forced to spend most of the night outside the police cordon, before being let in shortly after the first explosives were detonated at 9.40pm. Other families were told they could stay in their houses, but were required to have all their windows and doors shut. "All of a sudden the street became full of cops, then the bomb squad came. At the start they did not let us out of the house, but then they told everyone to leave because there was some explosive," a neighbour, who gave his name only as Bilal, said.

Police raid a property in Greenvale. Credit:Eddie Jim He said he heard what sounded like gunshots about 12.30pm. Dozens of armed officers arrived soon after, he said. He told Fairfax Media police said there might be explosives in the house. Police raid a property as part of a high-level counter-terrorism operation. Credit:Eddie Jim A man and several women are believed to have been inside the house targeted at the time of the raids.

Two young men driving a blue Holden Astra were intercepted by police in Somerton Road, only a few kilometres from Clare Boulevard, about 4.45pm, but it was unclear if the intercept was linked to the operation. Officers leaving a Greenvale property during counter-terrorism operation. Credit:Eddie Jim It is unclear if the operation, believed to have started on Thursday, relates to a specific threat made against police, but Victoria Police recently upgraded security measures for officers. A black armoured car, "massive, the size of a truck, big and black" was driving up the street, Bilal said. Witnesses also reported seeing two men led away by police into an unmarked police car. Officers wearing hazardous material or bomb disposal suits walked inside the house at the centre of the raids about 5.15pm.

Neighbour Nathan Sakellariou said unmarked vans and police vehicles were parked outside his house on Helmsdale Crescent, before descending on a home on the corner with Clare Boulevard about 2pm. He said he believed police had entered the property from the back fence. "There were Victoria Police in the divisional vans but definitely federal police in the (unmarked) vans and the Prado," he said. "They were masked up, you could literally only see their eyes even when they were sitting in the vans." "I thought it was a plumber and then all of a sudden they turn on their lights so they can go through the roadblocks."

Police were not releasing any information to neighbours, he said. "It looks like a normal a house, there's a basketball ring out the back." An SUV, parked in the driveway of a double-storey house on the corner of Helmsdale Crescent, appeared to have been ransacked. The bonnet of the car was also opened. A man who passed through the street about 2pm described a large police presence. "I saw a lot of police officers, a lot of white vans, and detectives," he said. Witnesses told Channel Nine that police arrived in a heavily armed vehicle and used a loudspeaker to demand any occupants come out.

A man reportedly emerged soon after and walked into the street with his hands behind his back. Police walked the man to nearby parkland where they sat him down. A short time later, six women emerged from the house and were escorted by police to another area. Police would not confirm if the operation was in relation to counter-terrorism, or which suburbs were being targeted. "Victoria Police, in conjunction with the AFP, is conducting a police operation in the northern metropolitan area this afternoon. As this relates to an ongoing investigation, it is not appropriate to comment further," a spokeswoman said.

It is understood that authorities have previously considered reducing the publicity surrounding counter-terror raids in a bid to defuse anti-Muslim sentiment. The Hume Islamic Youth Centre, in nearby Coolaroo, had not been impacted by the operation on Friday. The centre has previously been linked to extremism. An ASIO spokeswoman declined to say whether the agency was involved. "Unfortunately we are unable to provide comment as ASIO does not comment on operational matters," she said.

With Rania Spooner