Senior police fear an "emerging gun culture" in Melbourne's north-west may lead to innocent people being shot after a string of shooting incidents early Friday.

Assistant Commissioner Luke Cornelius said armed and newly-forming criminal networks were working together to carry out violent crimes, of joint benefit, as police work to halt the illegal gun trade.

Police examine bullet holes after a junior officer fired shots into the shoulder of a man at Tullamarine early on Friday. Credit:Joe Armao

Mr Cornelius said unlike gangs, the loyalties of these new criminal enterprises would shift depending on the crimes they were committing.

"This presents a considerable risk not only to my members but more particularly with the community," he said.