A grandmother has been senselessly attacked by juveniles while delivering food, with a big rock landing in her car after crashing through the back window.

Perth woman Dianne Sulman, 61, was attempting to break up a street fight in Merriwa on Wednesday when she instead became the target.

WATCH THE VIDEO ABOVE: Perth grandmother allegedly attacked by children while delivering food

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Rocks were thrown at her car, with a large one shattering her rear window.

“I was shocked. I wasn’t even aware that it was actually my car windscreen that broke,” she told 7NEWS.

“I thought it was something else, like a bad accident, it was that loud.

“And then when I realised what it was, I just started shaking, crying, realising what had happened.”

A rock was thrown through Dianne Sulman’s car as she tried to break up a street fight. Credit: 7NEWS

Sulman phoned her insurer and the police, still stunned by the sharp rock that had been launched her way.

“If that had hit me, it would have killed me,” she said.

The grandmother said she wanted to speak out after a Perth cyclist was injured when a rock was thrown at her only a month ago.

7NEWS understands another driver was targeted in this same area as Sulman just hours earlier.

“I hope that (the children involved) just learn from this and they stop doing it,” she said.

Sulman drives for DoorDash to make ends meet, but her car is now out of action.

While bystanders came to help her, she has been let down by her insurance.

Because those responsible are minors, they cannot be at fault, and she will have to pay the $150 excess.

Sulman said she could have been killed if the rock had struck her. Credit: 7NEWS

Her daughter Indahly launched an online fundraiser to help her cover the repair costs, with the family left overwhelmed by support from complete strangers.

“My mum is the most selfless person. She always puts others above herself,” Indahly said.

“Even in what happened yesterday, she was trying to stop a fight for the greater good.

“And of course it’s not ended so well.

“But she runs a food pantry for people, she’s a loving grandma, she’s a loving mum and for this to happen it’s devastating.”

Police are investigating and have urged others with similar stories to come forward.