Westlake Girls' principal Jane Stanley today told parents in an email that the injured students were starting to recover.
"One Westlake Girls student has now been discharged from hospital. Another student is stable and recovering from her injuries. The remaining student is still critically ill but is showing slight signs of improvement," she wrote.
She thanked the school parent community for their messages of support.
A school spokeswoman told the Herald the school had been overwhelmed by support from the community and neighbouring high schools, which have offered counsellors and relieving staff if needed.
Yesterday school staff had been at the hospital sitting with the injured pupils and their parents in the hours following the traumatic crash.
She said staff were now on high alert for pupils showing signs of distress and were focusing on looking after the girls.
A police spokeswoman said the serious crash unit was investigating and police "can't rule out the possibility of charges being laid".