Armed Crime Squad detectives and local officers, assisted by the Special Operations Group, arrested the trio about 6pm near the Werribee Plaza shopping centre and have taken them in for questioning.

The person who fired the shot, who police said was driving a stolen utility at the time, had been on the run since the incident, which took place in Hoppers Crossing just before 3.30am.

Two policemen on a routine patrol in a marked Ford Territory had tried to intercept a suspected stolen Nissan Navara utility vehicle on Derrimut Road, Werribee just before 3.30 on Thursday morning.

They began a short pursuit but pulled up after the ute drove onto the wrong side of the road and it was deemed to be too high a risk.

But instead of driving away, the ute did a U-turn before being driven back towards the police. A single shot was then fired into the driver's side door of the police vehicle.

No one was injured.

Detective Inspector Stephen Clark from the Armed Crime Squad said police believe there were at least two and possibly three people inside the ute.

"It's a real concern when anybody gets shot at but certainly the police and certainly in circumstances where there appears to be no reason for it," Inspector Clark said.

"The pursuit had been terminated, the car has come back from the other direction," he said. "Who knows what they were thinking."

Ballistics experts are analysing material from the car and the scene to determine what sort of weapon was used.

The police officers did not pursue the stolen car after the shooting, a police spokeswoman said.

Police and SES crews conducted a line search through the scene at about 7.30am, dropping one marker.

The shooting was in front of a school, and metres from a family restaurant and aquatic centre.

The Nissan Navara utility with the registration QYX759 was stolen from Braybrook on Monday night or Tuesday morning and is believed to be blue and silver in colour.

It was last seen heading north on Derrimut Road.

Police Association secretary Ron Iddles backed the use of helicopters or planes to track stolen cars, given the force abandoned road pursuits as part of a policy implemented earlier this year.

Detective Senior Sergeant Iddles said he supported the policy but admitted it was not popular with all members.

He said concerns about police officer safety were warranted, given police have been targeted in four separate incidents while attempting to intercept cars in the past eight days.

The use of helicopters or places to track stolen cars would be costly and require state government funding.

"The whole environment has changed," Detective Senior Sergeant Iddles told 3AW.

"Melbourne is now a 24-7 city, basically.

"We need to look at other technology and [helicopters or planes] is one option you'd look at."

The Hoppers Crossing shooting is at least the sixth this month and comes as dangerous firearm incidents have continued to escalate in Melbourne, prompting the creation of a new police firearms investigation taskforce on November 5.

The state government has also pledged to bring forward tougher gun trafficking laws and has legislated to make theft of a firearm a specific offence.

Fairfax Media last month revealed that a person has been injured or killed by gunfire on average every nine days in Victoria this year.

Police doing routine road operations were finding a gun in a car every two days in Melbourne's north-west in August.

Anybody who sees the Nissan Navara utility or has information about the shooting is urged to contact Crime Stoppers on 1800 333 000.

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