Person critically injured in seven vehicle crash on Auckland's Northern Motorway

One person has been critically injured in a large crash involving seven vehicles this morning on Auckland's Northern Motorway.

Emergency Services were notified of the crash at Dairy Flat about 6am.

The crash happened on the southbound lanes at section 2C, between the Silverdale off-ramp and the Oteha Valley Rd off-ramp, and near the Bawden St over-bridge.

NZTA says all lanes have been cleared and open but "significant congestion remains".

Motorists are advised to be patient or consider using alternative routes.