A taxi driver suffered head injuries after he was placed in a headlock and violently assaulted, police say.

The attack, believed to be carried out by two of four men the Tauranga driver had picked up, left the 40-year-old victim in hospital overnight.

Detective Sergeant Iain Chapman said members of the public came to the driver's aid, after the assault continued outside the vehicle.

The four men were picked up from the Welcome Bay shops and driven to Ohauiti Road.

"At the destination the driver was put in a headlock and attacked by the front seat passenger and one man in the rear of the vehicle."

Chapman said the driver managed to escape the taxi but was assaulted outside until a neighbour yelled at them.

The offenders tried to run off but about six members of the public came to the victim's aid and managed to hold down one of the men.

A police dog handler arrested another man a short time later.

Chapman said he had only praise for the residents who came to the aid of the victim.

"Although we never want the public to put themselves in danger we couldn't do the job that we do without the invaluable help of people willing to stand up for what is right."

Police were now seeking the other two men who were part of the group.

Police said they had CCTV footage from the taxi of a third man they wanted to identify.

It was not believed he physically took part in the assault but was with the men. They were also hoping to speak with the fourth man who was not captured on the camera.

Two men, aged 18 and 19 appeared in Tauranga District Court today charged with aggravated robbery.

They have been remanded in custody until their next appearance on January 29.

Police asked that anyone with information contact Detective Sergeant Chapman on 07 577 4300 or ring the anonymous Crimestoppers line on 0800 555 111.

- © Fairfax NZ News