“Initial information suggests that a car has collided with a bridge barrier and fallen into a body of water underneath,” a police spokeswoman said.
A Coastguard spokesperson said this afternoon that its staff had found the car in the waterway below the Ohau B canal bridge.
Questions about the driver and any passengers were referred to police.
One lane of the highway remains closed between Lake Ohau Rd and McAughtries Rd.
“The temporary road closures in the area will continue while the search is underway, to allow emergency services to access the search area safely,” police said.
“We wish to thank motorists for their patience, and to thank everyone who assisted with the search effort today,” they said.
Police, Coastguard and Fire and Emergency NZ were involved in the search, and local boaties were providing assistance.
A witness said the car appeared to have crashed into the High Country Salmon farm, just off Lake Ruataniwha.
There were at least four boats on the water searching for the vehicle, they said.