A pedestrian has died after being hit by a car on a busy road in Auckland.

Police were called just before 7am following a collision between a car and a pedestrian in rush hour traffic on Great South Rd in Ellerslie.

The pedestrian was taken to Auckland Hospital by ambulance in critical condition.

The Serious Crash Unit are on scene and Great South Rd. Police advised motorists to avoid the area.

St John said it was notified of this incident at 6.57am, responding with two ambulances and one rapid response vehicle.

Auckland Transport said motorists are being advised to expect delays, including to bus services.

Auckland Transport said several bus services have been impacted by the road closures, with bus stops being missed and routes being detoured.