A woman with her newborn baby buckled in the back seat had to take evasive action to avoid being hurt in yesterday's horror wrong-way motorway crash.

The woman, who did not want to be named, was driving in the southbound lane of the Southern Motorway from Mt Wellington heading toward Takanini at the time of the head-on crash.

The motorway was closed for two hours after a blue stolen car travelling on the wrong side of the road smashed into an innocent motorist.

"I didn't see the blue car right until the crash and just thought with my 3-month-old in the back how was I going to avoid it without someone crashing into the back of me.

"It was pretty horrific to see but I was quite calm and didn't slam on my brakes, I slowed and went as wide as I could around it."

The woman stopped 200m along the motorway and pulled over as police officers from cars in the northbound lane jumped the barrier.

A car following the woman parked in the lane to block traffic and "I assume, to protect the crash site".

"I was amazed how fast the police were there - it was immediately after the crash."

Realising there was no way she could assist anyone involved, the woman took a photo and left the scene.

"I drove up the motorway and within a few minutes, there were four more police cars and two fire engines."

Other members of the public who witnessed the car driving the wrong way on the Auckland motorway said they believed police vehicles were in pursuit.

The information is in contrast to what Police said yesterday - that there were no police cars following the car directly and it was only being pursued by the Eagle helicopter overhead.

Inspector Cornell Klussein said the Police Eagle helicopter had been following a car just before the crash about 10am.

"The person in the car was wanted for an unrelated serious crime. He started driving at high speed through roads like Te Irirangi Drive and around the Flat Bush area," he said.

"During this time, Eagle was following. We didn't have any police cars pursuing him directly. After a while, he entered the motorway going the wrong way at Highbrook."

Another police spokesman said police were not in pursuit but were several hundreds of metres back in the Highbrook Drive area preparing to lay road spikes.

"Police were nearby in the area in anticipation of the offender possibly dumping their vehicle and decamping on foot.

"This is a standard tactic by police when dealing with these types of situations."

Police said lights and sirens were not used before the crash.

A man turning into Rā Ora Drive - which runs off the busy Highbrook Drive - said he was just turning onto the median flush when he spotted the blue car make a dangerous move to get onto the main road.

Carl, who did not want to give his surname, said the driver of the blue vehicle almost failed to give way, turning dangerously into Highbrook Drive.

"He got onto [Highbrook] and gunned it. I saw the rear tyre, on the driver's side, was a little odd and realised it was completely shredded.

"I remember thinking: 'How can this guy not know he has a flat tyre'?''

Carl says he then saw at least two police cars coming down from Allens Rd, which merges into Highbrook Drive and possibly one that followed the car from Rā Ora Drive.

Only one of the police cars had their lights and sirens on, Carl said.

Another reader said he was waiting to turn onto Highbrook Drive from Business Parade North when the blue car "blew past me".

"We witnessed one of the shredded tyres come off as he changed lanes,'' they said.

"Within five to 10 seconds, two squad cars - lights blazing - blew past us in pursuit. Then another three to five vehicles after that."

The reader said they lost sight of the vehicles as they rounded a distant bend.

A truck driver who was coming off the motorway via the Highbrook off-ramp told the Herald yesterday he got a shock when he saw the blue car heading towards him.

"The idiot was going down the wrong way of the motorway. He just came flying past on the slow lane - but the wrong way. It was looking like he was trying to find a way to get off.

A woman with a newborn baby in the car narrowly avoided the head-on crash on an Auckland motorway. (Photo / Supplied)

"I thought: 'Oh here we go'.

"It just exploded. There was this massive explosion when he hit the other car head-on. It wasn't good to see.''

The man, who asked not to be named, said the car was travelling so fast he did not have a chance to react - whether it be to beep the horn or yell out to him.

He said today there were no police cars following the blue car down the off-ramp; but he did see police cars once he turned into the main road.