Family mourn pregnant mum hit with brick

The family of a pregnant mother killed in suburban Perth after being hit by a concrete block has been left devastated by the tragedy.

Diane Miller suffered a heart attack on Tuesday night when the block was thrown through the open window of her car at a Karawara shopping centre in what police have described as a senseless and unprovoked attack.

The 30-year-old Noongar woman died in hospital overnight after spending several days in a coma.

She was five months pregnant and also had an eight-month-old son. 

Family members gathered on Friday at the shopping centre, where Ms Miller's partner Phillip Edmonds described his shock at her passing.

"We all loved her as one and that's what brought us together," he said.

"That's my baby girl and that was my baby inside."

The 17-year-old boy who allegedly threw the concrete block faced Perth Children's Court on Wednesday charged with grievous bodily harm and breach of bail.

He was remanded in custody and is due to return to court on December 9.

His charges could be upgraded after West Australian homicide detectives took carriage of the investigation.

Police allege the boy had been one of a number of teenagers involved in an altercation at the shopping centre.

"This is, quite simply, senseless violence by a bunch of teenagers," Inspector Brett Baddock told reporters this week.

"From what we can gather, it's unprovoked. I think they've gone out looking for trouble and they've found it."

Members of the public tried to resuscitate Ms Miller before an ambulance arrived.

The family has remembered her as a happy and funny person and urged the community to let the police investigation unfold and refrain from any retribution.

Greens Senator and Yamatji-Noongar woman Dorinda Cox said Ms Miller's death was extremely upsetting for the local community.

She said it was another example of violence towards First Nations women which is the subject of a Senate inquiry.

"We cannot continue to allow this to happen," she said in a statement.

"I encourage family members who have been through similar tragedies to please make a submission to the inquiry.

"It's only through sharing our grief and loss that we can find solutions and stop this senseless loss of life."

Premier Mark McGowan said it was a shocking and awful incident.

"Everyone's terribly sorry for her, her unborn child and her family," he said.