The shooting of a police officer in Melbourne's north-west may be linked to an earlier attack on the home of George Williams, the father of slain underworld figure Carl Williams, police say.

A 31-year-old policeman was shot in the back of the head after he and his partner tried to pull over a car in Moonee Ponds about 3:40am on Tuesday.

Only 10 minutes earlier, gunshots were fired into the Broadmeadows home of George Williams.

His son Carl Williams, one of Melbourne's most high profile underworld figures, was bludgeoned to death in the high security Acacia Unit at Barwon Prison by his cell mate in 2010.

Victoria Police said shots went into the front fence of his father's house on Katandra Crescent and no one was injured.

On Sunday a number of Molotov cocktails were hurled at a home on Primrose Street, just blocks away from where the shooting at Moonee Ponds took place.

Roberta Williams, who was married to Carl Williams, lives nearby.

It is unclear if all three incidents are linked.

George Williams speaks to police after home was targeted. ( ABC News )

At the Moonee Ponds incident on Tuesday morning, two officers tried to stop a black car, but the driver sped off.

After a short pursuit, the officers tried to block the car with their van on Robinson Street but the driver steered around them.

He then fired one shot from a 12-gauge shotgun out of the window, hitting the male officer who was driving the van.

"Pellets have gone through the open window, injuring the first constable who was driving that van," Detective Inspector Steve Clark said.

"I'm pleased to say the injuries are not life-threatening.

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"As I understand it, it was only a routine intercept. Police have gone to pull that car over and it's sped away from them."

The injured policeman's fellow officer called for help and administered first aid until emergency crews arrived on the scene.

The injured officer was taken to the Royal Melbourne Hospital and is conscious and in a stable condition.

The car sped off and officers are looking for the gunman.

About 30 minutes later the car was found burnt out at Hossack Avenue in Coburg North.

Detective Inspector Clark said it was really only "good luck" that the officer was not more seriously injured.

"I'm told our police member has a number of shotgun pellets to the back of his head. I really don't have any more information about his condition at the moment," he said.

"It just shows how dangerous police work can be.

"Fortunately on this occasion it's a good news rather than a bad news story."

Interceptions among 'most dangerous duties' for police

The car believed to have been involved in the shooting was later found burnt out in Coburg North. ( ABC News )

Police Association secretary Ron Iddles said it was a "very tragic event".

"Something as simple as a routine check of a vehicle was turned into a tragedy," he said.

"It's not just about terrorism. It's about everyday police duties.

"Intercepting vehicles is probably one of the most dangerous duties that a police officer will carry out.

"Both members are extremely lucky not to have lost their lives this morning."

Mr Iddles said the incident showed no police officer should be working alone.

"This is a situation where one member was able to assist the other member last night, so I think that in itself is a positive move forward," he said.

"I've spoken to the passenger of the divisional van and I think the emotional scars will live far longer than any physical scar."

'Scary shooting in suburbia'

Local resident Helen Stanford said she was scared after she heard a "bang" in their street and suddenly there were "flashing lights everywhere".

"This is suburbia. For someone to have a shotgun in their car or truck or whatever it was, it is scary because you don't expect to pull over a car and have the gun shoot through the window," she said.

"I think this is a very sad thing."

Ms Stanford said it was fortunate the incident happened in the school holidays because it was very close to St Monica's Primary School.

"This is a school street," she said.

"Had this happened next week this would be full of cars and people dropping off children and children walking along the streets."