A principal says her college will keep promoting safety messages to young people after seven teenagers - three of them former students - were involved in a serious crash.

Two were seriously injured and three others suffered broken bones when an overloaded car crashed about 11pm on Friday on State Highway 16, south of Wellsford.

A boy and a girl, both 17, were in the boot and were thrown from the vehicle in the crash.

The boy was in Auckland City Hospital in a stable condition yesterday and the girl had been discharged. The two teens and one other passenger in the car were recent ex-students of Rodney College in Wellsford.


Principal Irene Symes said the crash was concerning for the school community.

"We'll do our best to continue to give those messages in terms of making the right choices," she said. "We're not ignoring this and we certainly will continue to promote those messages."

Waitemata road policing manager Inspector Mark Fergus said the crash was a reminder to parents to talk to their teens about being available to pick them up any time.

Police said the teenagers had been drinking at a reserve when they got into the car to go home. The 17-year-old driver did not hold a licence and lost control on a moderate bend, crossing the centre line and crashing into a ditch, where the vehicle rolled on to its roof.

Mr Fergus said the combination of risk factors should have been a red flag for the teens involved.

"All those risk factors should cumulatively say to someone, 'You know what, I'm not going to get in the car'."