Part of State Highway 1 in Waikato is expected to be closed for several hours after a crash south of Hamilton today.
Two cars collided on State Highway 1 near Whites Road, Putaruru, at around 1pm.
Two people are in a critical condition and two are in a moderate condition, a St John spokesperson told 1 NEWS.
An ambulance and a rapid response unit are already at the scene, with two more ambulances and a helicopter on their way.
The road is likely to stay shut for the next few hours, police said this afternoon.
The town of Putaruru is around 60km south of Hamilton.