State Highway 29 is now open after emergency services were forced to close the highway due to a car and truck crash.

Emergency services were called to the crash, near the Ruahihi Power Station, just before 2pm.

A caller to the 0800 SUNLIVE news hotline says a truck and trailer unit have rolled on to its side after crashing with a silver vehicle.

"Firefighters had to remove the driver from the vehicle.

"Traffic was backed up for miles,"

Three people were transported to Tauranga Hospital from the crash, says St John.

Diversion were in place, as the road was closed to allow for heavy haulage tow trucks to remove the 18 wheeler truck from the scene.

NZTA reports the highway is now open, almost six hours after the crash.

Police are still investigating the cause.

People who have information about the crash, and haven;t already spoken with police, are asked to contact their nearest police station.

Alternatively, information can be left anonymously via the Crimestoppers 0800 555 111 line.

Non-emergency information can be phoned into the police's 105 number,