Six teenage boys have been arrested following an alleged "crime spree" in Hamilton overnight during which they found a gun and ammunition in a vehicle they allegedly broke into.
It is one of three such incidents in recent days and police are concerned.
Inspector Greg Nicholls said police were alerted to the latest incident by a man who disturbed three boys breaking into his car in Hillcrest about 4am.
The man followed the trio in his car as they rode off on bicycles to nearby Hillcrest Park.
A dog handler tracked the group for about 3km to a Nevada Rd address where four teenagers were arrested. Two others were arrested later.
The group were suspected to have broken into at least 12 cars.
"Perhaps the most disturbing thing for police is that the offenders managed to take a .308 calibre rifle and ammunition from one of these cars," Mr Nicholls said.
The gun and ammunition were located at a property, with one of the alleged offenders.
Mr Nicholls said the fact an unsecured firearm was being kept together with ammunition in a car was a major concern and something that would be taken up with the owner.
In Christchurch last night, five 14-year-old boys were arrested after two cars were broken into in Burwood.
Detective Senior Sergeant Corrie Parnell said residents at a Chartwell St address called police about 11.40pm after seeing three offenders trying to break into their vehicle.
Police tracked the group and found them hiding in bushes nearby.
In another incident in Christchurch, a Burwood Rd resident disturbed a youth entering an unlocked ute parked in the driveway of the property about 1.30am.
The resident followed the offender and when police arrived shortly afterwards two youths were taken into custody.
Mr Parnell said it was possible the youths involved in the two Christchurch incidents were known to each other, and may have been involved in other offending.
Meanwhile, five teenage boys have appeared in Youth Court for another alleged "crime spree" in Waikato over the weekend.
The group are alleged to have taken a car in Auckland on Saturday afternoon and driven to Hamilton where they stole other cars - and property from them - and took them back to Auckland.
Police tried to stop one of the vehicles in Hamilton on Saturday night but the driver fled at speed.
The pursuit was abandoned, but the vehicle was seen by police in Huntly a short time later and followed until the fleeing car ran out of petrol.