CCTV footage has confirmed the offending vehicle had entered the Wellington Urban motorway northbound lanes at Petone.
Two vehicles collided in the northbound on the fly-over between Molesworth St and the Aotea on-ramp about 4.20am.
Two people died at the scene and the two in the second vehicle were taken to Wellington Hospital. One is in a serious condition in ICU, and the other is undergoing treatment, a spokesperson said.
After reviewing CCTV police have confirmed the vehicle in which two people died had entered the motorway by turning right into a northbound lane from Cornish St in Petone.
A woman driving to work told The New Zealand Herald she saw a car driving on the wrong side of the motorway.
"My co-worker was also coming to work at this time and saw far more than me - [he] was trying to signal the driver to turn around."
The woman said her colleague had seen the car get onto the motorway via the Petone entrance before it "sped off".
"[My colleague] was trying to alert oncoming drivers by flashing high beams and hazard lights."
The woman got off the motorway at the Aotea off-ramp and did not see another vehicle.
"The crash seems to have happened just after that," she said.
"It would've been just before 4.30am as that is when I started work."
The woman said her colleague suspected there was a possibility the driver going down the wrong side of the motorway had become confused about where they were going.
