Police are responding to an incident on the Northwestern Motorway, which was reported shortly before 3.15 pm.

A person has fallen from the Hobsonville Road overbridge onto the motorway and has died.

Police have closed the citybound lanes underneath the Hobsonville Road overbridge and citybound traffic on SH16 is being diverted at the intersection of Brigham Creek Road and Fred Taylor Drive.

Citybound traffic on SH18 is also being diverted at Brigham Creek Road.

The Hobsonville Road overbridge is also closed to vehicles and foot traffic at present.

Lane closures will be in place for some time and motorists are urged to avoid the area if possible and expect delays.