Police are investigating after a video attack on a busy Auckland motorway that was captured on video and shared online. 

Video of the incident, which took place on Monday afternoon on Auckland's Northwestern Motorway, was shared across social media. 

The video, shot by someone in a passing car, shows two men attacking another man as he lies on the road. 

Both men repeatedly punch the victim, before one delivers a kick to the head. 

Others then intervene, remonstrating with the assailants who are heard to claim that the incident was sparked by someone being cut off on the busy motorway. 

 

Video shows both men punching the victim. 

Police have said they were called to the incident and are speaking to the victim. 

"Police were called to a report of an assault on the Northwestern Motorway at 4.30pm on Monday," Police told Newshub. 

"Police are making follow-up inquiries with the victim and there have been no arrests at this stage."