The man arrested during a police hunt for gun dealers in Melbourne's north on Friday has been released without charge.

About 5am more than 150 heavily armed state and federal police officers raided three properties in Gladstone Park, Ascot Vale and Glenroy, hunting for the people who may have supplied Brighton killer Yacqub Khayre with the weapons used in Monday's deadly terror siege.

Another two search warrants were executed in West Meadows and Reservoir on Friday afternoon.

A 32-year-old man was arrested in Glenroy and two others were questioned in Gladstone Park - a 51-year-old father and his 31-year-old son - where an imitation gun was found.

However no one has been charged over the matter.

The AFP said the police raids were not in response to "any identified threat", but about the supply of firearms following the terror siege in Brighton in Monday.

"A number of items have been taken for further examination including an imitation firearm, computers, mobile phones and other material," an AFP statement said.

Victoria Police Deputy Commissioner Shane Patton said the raids were a part of an investigation into where the Brighton gunman obtained the two firearms - a shotgun and sawn-off shotgun- he used during Monday night's deadly siege.

Yacqub Khayre, 29, shot dead receptionist Kai Hao at the Buckingham International serviced apartments on Bay Street on Monday, before taking a sex worker hostage for hours. Khayre was later killed in a shootout with police. The sex worker was tied up, but was not physically injured in the siege.

It is believed Khayre took the woman hostage in a bid to lure anti-terror police to the scene.

None of the men were of national security interest, he said, but were known to police for other criminal offending.

"There's no intelligence or evidence at this stage to suggest that there is any connection to the people who we have spoken to, the arrest we made, and terrorism," Mr Patton said.

But the Australian men could face charges of aiding and abetting terrorism, which carry a life sentence.

"I take my hat off to our own special operations group when they've had three members of their unit shot on Monday night, two hospitalised with very serious injuries, and here they are this morning, quite courageously, executing warrants in premises where they don't know what they're walking into," Mr Patton said.

Earlier on Friday, residents in Ascot Vale described seeing police rummage through bins on Epsom Road as part of the raids..

One resident told radio station 3AW he saw "10 to 15 police searching rubbish bins" and in addition, had pulled a garbage truck over.

At the same time, a group of AFP officers - some wearing masks and others in plain clothes - searched a housing commission flat on Churchill Avenue in Ascot Vale.

Residents watched on as police gathered evidence from a balcony.

Resident Vinny Dee said he was woken by the noise of officers forcing their way inside the apartment.

"When I heard police getting through this morning I thought it was something to do with drugs," he said.

"It was loud, they struggled to get in."

Mr Dee said the apartment area had a problem with crime, particularly home invasions.

"It's the Bronx, man," he said, when asked about the area.

He said he did not know who lived in the apartment, but he had noticed a camera in one of the windows.

"Although it's very loud, I've never seen anyone go in or out," he said.

One local told 3AW he saw about 20 police running on a major road and SOGs "driving like mad" through another suburb in Melbourne's north.

"They're in transit, but they're obviously close because they're running. The cops were running and the SOGs were following at a rate of knots," the caller said.