Alcohol is believed to have played a role in a head-on crash early this morning, when a woman drove 5km the wrong way on the Southern Motorway.
Police said the female driver of a gold Nissan car got on the Mt Wellington off-ramp around 12.40am and drove south for about 5km in a northbound lane.
She swerved past a number of vehicles before crashing head-on with a car travelling north near the East Tamaki motorway on-ramp.
The woman and the driver of the other car - both the sole occupants of their vehicles - were taken to Middlemore Hospital in a critical condition.
Alcohol is believed to have been a factor in the crash, police said.
Police are investigating the crash and encourage anyone who saw the crash to come forward.
"We are hoping to speak with anyone who may have seen a silver Toyota Celica heading towards the Mt Wellington Northbound off ramp at around 12.30am this morning," Senior Constable Karl Bevin from the Waitemata Serious Crash Unit said.
The crash was a "very disappointing" start to the long weekend, he said.
The motorway was closed following the crash until 4am.
Anyone with information can call the Waitemata Serious Crash Unit on (09) 481 0773.