Seven of the youths admitted charges in Manukau Youth Court relating to the bashing of the policeman in Tuakau, 55km south of Auckland, last year as he attempted to break up a fight.
Charges against a further three were found proved following a defended hearing before a judge. Another teenager was cleared of the charge at a defended hearing.
Laws surrounding Youth Court hearings mean neither the youths, all of whom were between 14 and 16 at the time of the incident, nor the victim, can be named.
The seven who admitted charges included the youth who inflicted the most serious wound, a kick to the head while the policeman was on the ground which required a titanium plate to be inserted. He admitted a charge of wounding with intent to cause grievous bodily harm.
Manukau Youth Court Judge Ida Malosi indicated today he was set to face the highest sentence that the Youth Court can hand out: six months' of residential supervision. There will be a following sentence of supervision to come after his residence is completed.
The other six who admitted their roles in the attack were facing charges of wounding with reckless disregard.
Four of them have been sentenced to supervision with activity for six months -- the second-highest sentence available at Youth Court, which requires them to undergo various activity programmes and courses as directed by social workers -- with a further six months' supervision to follow.
A fifth was sentenced to six months' supervision, while a sixth will be sentenced in Manukau District Court.
The three who unsuccessfully defended their charges at a 2-1/2 week hearing in February have yet to be sentenced.
Two men who were over 16 at the time of the offending are due to stand trial later this year
The off-duty policeman had been running with his dog when he noticed a fight starting and tried to break it up.
He was set on from behind and several young people either punched or kicked him.
After he fell to the ground, one youth kicked the policeman hard in the head before being pulled away.
He was treated in Tuakau but lapsed into unconsciousness and was taken to hospital, where he had emergency surgery to have a titanium plate inserted in his head.
He suffered a fractured skull, a broken jaw, several broken bones in his face, missing teeth, a broken ankle, a collapsed lung and bruises and abrasions.
Police told NZPA the officer was still recovering from his injuries.
