Police said the 18-year-old male victim had "moderate injuries".
"Police continue to make inquiries into the circumstances of the incident."
The Youth Court deals with offenders aged 14 to 17.
Auckland District Health Board said the victim's condition on Sunday morning is now "stable".
Ōrewa College principal Greg Pierce said the college would contact police on Monday morning to find out what happened and whether college students were involved.
"We did have a cricket team that was playing nearby and possibly some of the boys may have witnessed what happened. We will be following that up on Monday," he said.
"We'll be doing whatever we can to help clarify what actually happened."