UPDATED: Two people are in a critical condition following a crash south of Hamilton this morning.

Diversions are in place around the scene on State Highway 1 near Bollard Road at Tamahere, says a police spokesperson.

The Police Serious Crash Unit is in attendance.

EARLIER:

State Highway 1 at Tamahere, south of Hamilton, is blocked following a serious crash.

Emergency services were notified around 6.40am of the crash between a truck and a van near the intersection with Bollard Road, says a police spokesperson.

"Indications are that there are serious injuries.

"Motorists are advised to expect delays."