Emergency services are responding to a serious two-vehicle crash on State Highway 1, north of Wellington.
The crash was reported about 4.40pm in the southbound lanes of the Johnsonville-Porirua Motorway, between the Tawa-Grenada North on-ramp and the Churton Park-Glenside off-ramp.
One person is understood to have serious injuries.
The Serious Crash Unit has been notified.
Motorists heading south on State Highway 1 should expect delays and avoid travel if possible.