UPDATE 10.25am: A SunLive reader says State Highway 29 is reopen under traffic management after a serious crash closed the highway earlier today.

A Waka Kotahi spokesperson says to expect "delays" when travelling through the area.

EARLIER 9.34am: State Highway 29 is closed following a serious crash between State Highway 1 and Totman Road.

A Waka Kotahi spokesperson describes the crash as a "serious incident".

"SH29 is closed between SH1 and Totman Rd. Please delay your journey or use an alternative route.

"Follow directions of emergency services."

A SunLive reader at the scene says traffic is backed up "about 500 metres" in the Hamilton bound lane.

"There are about three ambulances and five police vehicles. Two cars had a high speed head on crash."

A police spokesperson says police were called at 8.55am.

"Early indications suggest one person has sustained serious injuries.

"Traffic management is in place.

"Motorists are advised to avoid the area if possible, or expect delays."