Multiple vehicles have collided on State Highway 1 north of Levin on Wednesday morning, with one person understood to be seriously injured.
"Initial indications are that one person has sustained serious injuries and the rescue helicopter has been dispatched," a police spokesperson told Newshub.
A spokesperson for Fire and Emergency New Zealand (FENZ) confirmed the collision involves two cars and two trucks, with one person "heavily trapped".
Emergency services are at the scene and working to free the person, they said.
The road is currently blocked, with diversions in place at Koputaroa Rd and Tavistock Rd.
"We urge motorists to be patient, and to otherwise avoid the area if possible."