Senior police in Perth say they cannot find a justifiable reason why an officer fired several shots at a car that contained five people, including a child.

Police have launched a high-level inquiry into the shooting which occurred in the suburb of Nollamara yesterday afternoon.

They say senior constable Niko Westergerling stopped a black station wagon in Flinders Street containing four women and a three-year-old boy.

It is alleged the driver gave a false name and when the officer challenged her she drove off at high speed.

Detective superintendent Tony Flack says the senior constable drew his service revolver and fired at the vehicle.

He says the use of the firearm was highly inappropriate.

Police launched an inquiry after a male officer in this car fired shots at another car ( ABC News )

"There are other methods for stopping, detaining motor vehicles and the WA Police do not condone the use of firearms to stop motor vehicles," he said.

"That discharge was made in a suburban area, occupied by a number of houses and the potentiality and the danger will be assessed as part of our investigation in determining if charges should be laid and what type of charges should be laid."

Senior constable Westergerling has a prior assault conviction after pleading guilty to punching and kicking his wife during an argument at their home on Valentines Day this year.

It is understood he is also being investigated by police internal affairs for allegedly using the secure police database to access information unrelated to his police work.

Superintendent Flack says the officer has been stood down while the circumstances surrounding yesterday's shooting are investigated.

"Our interim finding [is] there does not appear to be any valid reason for the discharge of the firearm," he said.

"He does have a [previous] incident that we will assess in its totality," he said.

"Then we will make a recommendation to the Commissioner about things like judgment, practical intelligence, tolerance to stress, which the Commissioner needs to assess in determining this officer's suitability.

Officers are interviewing the occupants of the car which was shot at.

The car, with five people including a child in it, was shot at by a police officer ( Grant Wynne: ABC News )

Flabbergasted

The head of the Aboriginal Legal Service, Dennis Eggington, says he is stunned by what happened.

"Absolutely flabbergasted. I would think there needs to be a full investigation," he said.

"We just can't have this sort of thing happening on our streets where people are being fired at, particularly of late when there's been lots of, I guess, tension between Aborigines and the police."

Mr Eggington says the investigation needs to get to the bottom of what happened.

"It's not good enough with people shooting around the streets particularly now that the senior police have come out and said they can't find any lawful reasons why," he said.

"Even if these [people] could come to the Aboriginal Legal Service, we will make sure they're kept safe and sound and they can get their side of the story across."

Too early

The Police Union is calling on senior officers to complete an inquiry into the shooting before deciding if the officer was justified in discharging his weapon.

Union spokesman Russell Armstrong says it is too early to make a judgment.

"They can stand the officer down and charge him criminally or he could be charged with a disciplinary offence, but I think it's too early to make any call on if the officer was right or wrong," he said.

Premier Colin Barnett says he wants to know the full details of the incident.

"I am concerned. It seems to be a very strange event to have taken place, but I will wait until we have a proper report coming through from the police," he said.

Police are appealing for witnesses to the shooting.