Violent Vic car-jack trio on the loose

Three men armed with knives and wooden bats who went on a violent crime spree through Melbourne over the weekend are still on the run.

Police say the trio, believed to be in their late teens or early 20s, attempted to steal a car about 2.50am on Saturday in Mickleham, but the car's occupants drove off.

It is then believed the men - armed with knives and wooden bats - stole the car and belongings of a 22-year-old man in the nearby suburb of Craigieburn.

While driving in the man's Holden Commodore, police believe the trio targeted a group of people walking nearby, hitting a 40-year-old woman in the head with a wooden bat.

The woman was taken to hospital with non-life threatening injuries.

About 5am, the group held up a service station in Brooklyn, demanding cash and cigarettes.

They then attempted to steal the car of a man filling up with fuel outside, but he pleaded with them and the men left without taking anything from him.

Police are examining CCTV as they search for the trio.