Police seized a green cartridge and a large number of bullets in two raids in Melbourne's North District on Friday morning, the Herald Sun reported.
A man was arrested inside a house in Brunswick, where police officers searched the house in Hope St and questioned a man outside the house.
A garage in Buch Ave,Epping was also searched by police.
Senior police officer Darren Humphries said the raid was linked to organized crime. This follows a series of cases in the, Port Melbourne and South Melbourne regions.
Darren declined to reveal the nature of the incident, but he said it also involved drug.
"this investigation has something to do with drug, but it also involves other crimes."
Darren said a 28-year-old man has been detained and is assisting police investigations and will be charged in the afternoon, while the police are still searching for another man.
Darren said it was only a matter of time before the other man was arrested. " I think we will find him as far as the help we have so far is concerned. "
Neighbors said they heard screams from the Brunswick house around 06:15.
Police are expected to come regularly to the house, home of a Middle Eastern family, which is covered by surveillance networks. "as soon as I saw the police car this morning, I wanted to do it again," said a neighbor.
Police used a loudspeaker this morning to get a man out of the house.
The neighbors heard the police at about six o'clock in the morning.
One neighbor said: 'they yelled,' hands up. It took about 10 minutes for them to come out, and there have been previous raids on such homes by the police at SWAT,.'
Many neighbors described the anomaly of the house. "there are a lot of luxury cars that seem to have something to do with the house."
Another man earlier yelled at the media gathered outside the house.
"all the neighbors have to face this mess, it's really noisy."
It was reported that at least a dozen police officers were inside the house, and they could be seen moving evidence out in brown paper bags.
There are two luxury cars parked outside the house.