The Remutaka Hill Rd section of State Highway 2 near Wellington is closed due to a car fire.
Fire and Emergency said they were called to the car fire just after 12pm, which has now spread into surrounding scrub.
Crews, including a helicopter, are currently working on putting the fire out, which has spread up the hill about 500m².
Video footage captured by a passing motorist shows a car parked on the side of the highway completely engulfed in flames, and large plumes of smoke rising into the air.
Flames can also be seen spreading up the bank beside the vehicle.