Police are seeking witnesses to a high speed crash on the Southwestern motorway on Monday that injured multiple people.

A dashcam recording has captured the appalling moment a car sped up a bus lane and smashed full speed into multiple other vehicles.

Dashcam owner Ben Comemadang spoke with the Herald yesterday and said the car was driving very fast on the bus lane before it hit a Mazda SUV and sent it careening into bush on the side of the road.

The driver then proceeded to crash into multiple other vehicles, before also ending up on the side of the motorway.

The damage done to the Mazda SUV after it was ploughed into by a speeding driver. Photo / Supplied
The damage done to the Mazda SUV after it was ploughed into by a speeding driver. Photo / Supplied

A police spokesperson said the incident involved six vehicles, and three people were taken to hospital - one with serious injuries.

"Police spoke with a number of people at the scene and our inquiries are still ongoing into the crash," they said.

"We would like anyone who witnessed the crash or saw the silver Subaru prior to the crash to contact police on 09 481 0330."

Himesha Fernando, 21, was driving the Mazda SUV when it was suddenly hit from behind.

"I was driving home from Manukau and we didn't see any vehicle coming from behind us but suddenly someone randomly crashed into our car," she said.

"We were thrown across the road towards the bush. It was super fast and hit us so hard.

"It was definitely shocking. Me and my friend were screaming and shaking. We didn't know what was happening because it came out of nowhere."

Fernando injured her leg, tearing a calf muscle, and was unable to walk after the crash.

She was taken to Middlemore Hospital.

After seeing the dashcam footage, Fernando realised how lucky she was to be alive.

"It is pretty horrible. That is unacceptable driving," she said. "According to the video it looks like we shouldn't even be alive."

She hoped police would charge the driver.