One person is seriously injured after the car they were in crashed into a creek in Northland.

The car came off the road at State Highway 1 and began sinking in what is believed to be a small creek in Otaika, 10 kilometres south of Whangarei, at Oakleigh Rise, around 2.50pm.

It is not yet known how many occupants were in the car at the time, but one person is believed to have suffered a broken leg, said Inspector Lou Alofa.

All occupants have now been safely rescued from the car, he said.

No other vehicle appears to have been involved in the incident, Mr Alofa said.

There are no road closures in place but motorists are advised to take care.

The serious crash unit is at the scene and has begun an investigation into the crash.

- APNZ