A domestic incident at a Ranfurly business last Friday night left the female victim unconscious and needing hospital treatment, along with the assailant who was attacked by her family.

Alexandra Police Senior Constable Graham Perkins said the man, who was in his late 30s, took exception to his girlfriend having work drinks with other male colleagues.

After allegedly assaulting her with blows to the face and head, knocking her unconscious, she was taken to Dunedin Hospital with suspected head injuries. Meanwhile, her family then stepped in and allegedly assaulted the offender and he was taken to hospital as well.

Snr Const Perkins said the man was charged with assault with intent to cause grievous bodily harm as well as intent to injure, and was in custody with further investigations underway.

Meanwhile, in Roxburgh on Monday night, a man in his 30s, recently released on bail from Napier, was intoxicated and started assaulting his new neighbour after a verbal altercation.

The victim was in his 50s and an older man riding a bicycle across the bridge came to his aid, calling police, before the offender threw his bike into the bushes and came after him too.

Snr Const Perkins said the neighbour tried to distract the offender so the other man could get his bike back, and when a second neighbour offered assistance and then retreated inside, he had rocks thrown at his house.

Eventually the offender ran away before Snr Const Perkins found him walking down the main street where he was promptly arrested. 

Seven police units from Dunedin, including the tactical dog team with an Armed Offender Squad member were called for assistance, but later stood down by Snr Const Perkins when he made the arrest.

The offender is in custody awaiting a court hearing and has been charged with assault with intent to injure.  

Snr Const Perkins said he was still wanting to talk with the older man with the bike to see if he was okay.

In terms of the community coming to the assistance of victims, he said it was better to be a professional witness from a safe distance and try and record the incident.

Citizen arrests where people tried to contain the victim themselves was not recommended unless they had the necessary skills to deal with it.