The sole survivor of a two-vehicle head-on crash near Thames remains in hospital in critical condition.

A married couple, both in their 60s, and a 20-year-old man died at the scene of the crash on State Highway 25, west of the Kopu Bridge just after 8.30pm.

Preliminary indications were that one of the utes crossed the centreline, says Waikato Senior Sergeant Charles Burgess.

The two vehicles then crashed head-on.

"Sadly both the couple in one ute died at the scene, along with the driver of the other ute."

The couple were understood to be locals to the Thames area.

The Thames Volunteer Fire Brigade was also called to the scene of the crash.

In a post on its Facebook page, the brigade offered condolences to the families of those who died.

'Called to an incident just west of the Kopu Bridge where two utes collided head on, each carrying two people.

'We began extrication of the sole survivor who was flown to hospital.

'We send our sincere condolences to those families affected by the loss of their loved ones.”

The highway was reopened around 4am.

-Additional reporting by Stuff.co.nz