A woman who allegedly stabbed her two children on a motorway in Adelaide has faced court as police praised a man who intervened in the incident, declaring his actions prevented a far worse situation.
Police say the woman stopped her car on the North-South Motorway late on Monday night and removed her two young boys before stabbing them both several times with a knife.
A member of the public stopped his car on the motorway and intervened, disarming the woman.
He was assisted soon after by two other members of the public, who restrained the woman until police arrived.
Superintendent Selena Dinning said police were extremely grateful to the man and the other people who helped.
"If this man hadn't stopped, I'm sure the situation would have been much worse," Supt Dinning said.
"We're very grateful that he stopped and we're also very grateful to the two other members of the public who assisted him.
"We think he was very brave in doing this. We are really pleased that he was there - right spot, right time."
The two boys were taken to the Women's and Children's Hospital in Adelaide where they were treated for critical injuries.
The eight-year-old had surgery on his wounds early on Tuesday and was expected to make a full recovery.
His three-year-old brother was also expected to be operated on with his condition described as stable.
Their 35-year-old mother was taken to Royal Adelaide Hospital where she underwent a medical assessment.
Megan Somerville later faced a bedside court hearing charged with two counts of attempted murder.
Court documents showed she was remanded in custody to appear again in December though her lawyers were granted leave to call on an earlier bail hearing.
Supt Dinning said it was not known what triggered the incident or where the woman was going.
"She was on the expressway, so it's not that far (from her home) but why she was there, I can't say," she said.
Previous dealings between the family and police and child protection services will be investigated, and form part of the material put before the court.
Police will also liaise with authorities about the ongoing care of the children but have already identified other family members, including the father of the two boys.
Premier Peter Malinauskas said reports of the incident were "clearly shocking".
"There are so many questions that are unanswered here. It's appropriate for the police investigation to run its course," he said.
"It's impossible to get your head around. If the allegations are proven to be true, God knows what circumstances have led to this absolute tragedy."
