One moderately injured after crash on Auckland's Northwestern Motorway

A person has been injured after a crash on Auckland's Northwestern Motorway.

Emergency services were called to the incident, near the Patiki Rd exit, about 10.30am.

Two people were treated by paramedics at the scene and one was taken to Auckland City Hospital in a moderate condition, a St John ambulance spokeswoman said.

A truck and a car were reportedly involved in the collision.

Meanwhile, traffic is crawling on State Highway 1 north of Auckland as revellers head out of the city for New Year holidays.

A bus has broken down near Warkworth and is blocking one lane at the passing lane.

The road is expected to be congested between Puhoi and Wellsford until about 5pm.

The Southern Motorway is also likely to be busy until 6pm.

Police have also warned motorists driving in the Coromandel to be patient.

Traffic is starting to build-up in and around Tairua.