Rescuers are struggling to reach a vehicle stuck underwater and believed to have a person inside, in the Hunterville area.

It was understood that a vehicle drove off Turakina Valley Rd about 9pm and ended up submerged in a river.

Police Inspector Steve Mastrovich said a specialist dive team was travelling from Wellington to assist, after local emergency crews were unable to reach the vehicle.

"All that is known at the moment is that there is an unidentified car submerged in a river," he said.

"It is assumed that there is at least one person in the vehicle."

Mr Mastrovich said no further information will be released until after the dive squad has arrived and assessed the scene.