A serious collision between a car and truck has forced State Highway 1 to close through Te Horo, south of Otaki.
A Central Police spokesman said police were called to the incident at 2pm.
It was too early to tell whether anyone had been injured in the collision, he said.
Diversions were in place and motorists were advised to expect delays.
"[It was] a serious motor accident. We're advising motorists to delay travel or be patient while police and emergency services deal with the situation.
"The whole road's blocked. There are diversions and people just need to know when they get there, they'll be diverted," he said.
It is understood the incident occurred near the State Highway 1 intersection with School Rd.