Three men were to appear in Oamaru District Court on Monday on charges relating to an attack on a police officer.
The officer was conducting driver alcohol testing on Sunday night when he was set upon in what police have described as an unprovoked, gang-like attack.
He suffered leg, arm and facial injuries but has been released from hospital.
A 20-year-old Oamaru man has been charged with unlawful taking of a motor vehicle, excess breath alcohol, failing to accompany a police officer and aggravated injuring.
An 18-year-old man has been charged with aggravated injuring, while another 18-year old is facing a charge of theft of a breath-testing device.
It is the third attack on a police officer in three days.
On Friday, Constable John Connolly, 39, suffered multiple injuries as he tried to break up a fight between two teenage girls in Tuakau, south of Auckland.
Police say he was set upon by youths who had been watching the fight, suffering a fractured skull, a punctured lung, serious facial injuries, a broken jaw, a broken ankle and missing teeth. Police expect to make arrests by Tuesday.
Superintendent Mike Bush says Mr Connolly was having a metal plate inserted into his head on Monday to fix fractures to his skull and face.
In Whangarei, an officer suffered serious facial injuries after an assault by a suspected drunk driver on Friday night. The constable underwent surgery on Sunday and surgeons were able to restitch his lower lip.
A 29-year-old man has appeared in Whangarei District Court facing charges of wounding, assaulting police, threatening to kill, resisting police, driving while disqualified and refusing to give a blood sample.
Students likely to face disciplinary action
Tuakau College principal Chris Betty says students involved in the attack on Friday are likely to face disciplinary action.
Mr Betty held a special assembly on Monday morning and appealed for information from students.
The school's disciplinary processes will begin after the police investigation is complete, he says.
