Two of the youths were 12, two were 13, one was 15 and one was 16.
Kāpiti-Mana Area Commander Inspector Tracey Thompson praised the work of officers who located the young people and thanked members of the public who called police.
Thompson said the age of the group was a "real worry".
"I'm aware that the recent spate of vehicle thefts is something our Kāpiti community are really concerned about. It's not an issue police can address alone.
"We need all of our whānau and community to wrap themselves around vulnerable young people to steer them towards better outcomes."
Kāpiti Coast district mayor K Gurunathan said residents had alerted him to an increase in vehicle-related crime in recent months.
He applauded the quick actions of local police officers in corralling the six culprits.
"Like the police, I am concerned by the young age of these offenders and the cultural influence of social media that we've seen in other similar youth offending."
He said it was a community issue that needed the knowledge and expertise of schools, parents, caregivers, providers and frontline practitioners to address.
"This antisocial behaviour can't just be a problem for police to clean up – that's like parking the ambulance at the bottom of the cliff."