Just before 11.30pm on Monday, police were called to a motorway in Wingfield, in north Adelaide, after a member of the public phoned to advise a woman had been detained.

"Police will allege that the woman stopped her car and removed her two young children before stabbing them with a knife," a South Australia Police spokesperson said.

"A member of the public stopped his car on the motorway and intervened, disarming the woman.

"Soon after he was assisted by other members of the public who restrained the woman until police arrived."

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The two young children, who live in Modbury Heights in northern Adelaide, were taken to the Women's and Children's Hospital where they were treated for critical injuries.

They remain in hospital in a stable condition.

"The woman, a 35-year-old from Modbury Heights, was arrested and taken to Royal Adelaide Hospital where she has been detained and will likely be charged with two counts of attempted murder," the police spokesperson said.

Detectives are investigating the incident and ask anyone who may have witnessed the incident and haven't already spoken to police to please contact Crime Stoppers on 1800 333 000.