Adelaide student refused bail over 'classmate stabbing at private school'

A court has heard a young girl accused of stabbing a fellow student at a prestigious Adelaide Catholic school ambushed her alleged victim in a random and unprovoked attack.

The teenager is accused of knifing a 17-year-old girl in the back at St Dominic's Priory College, sending the North Adelaide into lockdown just before 3pm yesterday.

She was taken to the Women's and Children's Hospital for treatment.

The court heard the alleged victim was washing her face in a toilet block, when the accused approached from behind, stabbing her with a folding knife and saying "I'm sorry" before running off.

Further details were revealed in court, then suppressed.

As students returned to school today, parents remained in shock.

"Very tragic what happened and the girls, well we're all affected," one parent said.

Another telling 9NEWS, "You bring your girls to school to be safe but seeing and hearing that kind of stuff just makes you worry a little bit."

The incident is the second school stabbing in South Australia in the past week.

A 17-year-old girl was allegedly stabbed by her 18-year-old classmate Amber Rover at Renmark High School last Tuesday.

But the Police Commissioner Grant Stevens said there's no cause for concern.

"I would not like to see an overreaction to two separate incidents," he said.

"Statistically, this is not something that would concern us but the incidences themselves are being treated seriously and being investigated appropriately."

The girl was denied bail to reappear in court next Wednesday.