A 14-year-old boy is facing 81 charges after serious incidents in Christchurch including assault and aggravated robbery over the last week.
Police said in a statement four youths have been arrested, three on Thursday, and after extensive enquiries, a fourth on Saturday morning.
The 14-year-old faces 81 charges including assaults with intent to injure, unlawfully taking a motor vehicle, aggravated robbery and theft.
He is expected to appear in the Youth Court on Monday.
Christchurch Metro Area Commander Lane Todd said the other three youths arrested will be dealt with by Youth Aid.
Todd is confident the four arrested are allegedly responsible for recently reported incidents of car theft and assaults across the city.
"We're pleased to have quickly and comprehensively tackled what has been a significant run of offending by a small group of young people," Todd said.
"However it's hard to see these apprehensions as anything more than an inevitable end to a story that started long before any offence was committed.
"It's very rare that youth offenders come 'out of the blue'. We encourage communities to reach out to police if they're seeing concerning behaviour amongst their young people."
Todd said police hired a helicopter to find and arrest the 14-year-old who posed a "serious risk to our community and themselves".
The arrest comes after several videos emerged online showing children being attacked on their way home from school in Christchurch.
Newshub has been sent multiple videos of the brutal and random beatings which are believed to be linked.
One video shows a small boy being kicked in the head in an unprovoked attack. The alleged offender then runs to a waiting car while the victim runs away.
Todd said tackling serious crime takes a multi-agency approach, with prevention at the heart of any solution, along with alternative resolutions for offenders in an effort to break a cycle of offending.
"In Christchurch, like many centres, we run multi-agency programs to support wider whānau who are struggling with tamariki behavioural issues," Todd said.
"There are many factors driving youth offending and it takes a wide, focused approach keeping whānau in the centre of developing solutions.”
Police said they're working with Oranga Tāmariki and the Ministry of Justice, to address the drivers of this offending by young people.
"Police's role is very clear: we have an obligation to the community, and we will respond, investigate, apprehend, and hold people to account," Todd said.
