Whanganui police say three teenagers drove around the Westmere district on Saturday night firing guns at houses and letterboxes.
They say it was not just hi-jinks but potentially a very serious incident.
Several phone calls were received just before mdnight from worried from Rapanui Road residents who could hear shotgun and rifle fire.
One man said his front door had been shot through. Others said their letterboxes had been fired at.
Police say that shortly afterwards officers stopped a car in which they found a 15-year-old and two 16-year-old youths, together with a 12-gauge shotgun, a .32 rifle and ammunition.
Sergeant Colin Wright says police will be speaking to the owner of the guns - the father of one of the teenagers - about how the youths got access to the weapons, and about their behaviour with them.
Alcohol was not involved, he says, and the trio have been referred to Youth Aid.