State Highway 1 has been closed temporarily following a crash south of Waipu.

Emergency services were called to the crash near Finlayson Brook Rd about 6pm (Sunday).

One person in serious condition was trapped in a car while four others were being treated by St John at the scene.

Rescuers were working on freeing the trapped person and the Northland Electricity rescue helicopter was put on stand by. The police serious crash unit were called to the scene. Diversions are in place.