A traffic controller was allegedly beaten up after telling two men he did not have time to give them a cigarette.
The two men started a conversation with the worker while their vehicle was stationary at the Springvale Rd roundabout.
The 60-year-old was stemming traffic congestion as resealing was carried out on London St when the assault occurred at about 5.30pm last Friday.
The worker asked the two men to move along so traffic could continue flowing, but they got out of their vehicle and attacked him using their fists and feet.
A witness to the incident who did not want to be named said two members of the public then got involved.
"They were in vehicles, just innocent people trying to intervene which is really great, but they ended up on the worse side of it," he said.
"They both ended up being taken to hospital."
The traffic controller was also taken to hospital with bruised ribs, black eyes and a swollen face.
The witness said the scene was shocking but it could have been worse.
"If not as many people got involved, it could have escalated. There were truck drivers getting out of their vehicles after the first two were attacked," he said.
"That defused the situation. It happened in broad daylight in congested traffic, that was lucky, because if it wasn't as busy, it could have been much worse."
A police spokesperson confirmed officers were investigating an assault on two men, involving three offenders.
In 2013, George Taiaroa, 65, was shot dead as he operated a stop-go sign at roadworks near Atiamuri. Quinton Winders, 46, was later convicted of murdering the road worker. The court heard he had been enraged by a minor traffic incident a week prior to the shooting.