Two people have been critically injured and a third is in serious condition following a crash on State Highway 27.

The highway at Waharoa, in the Matamta-Piako district, was closed for several hours as emergency services worked to clear the crash scene.

Emergency services were called to the crash involving a truck and a car at 8.45pm.

"Three people have been taken to Waikato Hospital, two in critical conditions and one in a serious condition," says a police spokesperson.

The road was closed at Jagger Road and Walton Road.

It was re-opened just after 3am.

The Serious Crash Unit is investigating.