Guns and ammunition were stolen from a ute taken from Cromwell for a 120km joyride early on Saturday.
''Obviously, the people or person responsible have obtained those firearms unlawfully and we have grave concerns about whose hands they are in,'' Sergeant Simon Paget, of Cromwell police, said.
''It could be kids ... it could be anyone. There was ammunition taken as well, so we're very concerned about that fact, too.''
The guns taken were a Bruno .22 and a 12-gauge Stoeger shotgun.
The late-model white Mazda 4x4 ute was taken from outside a Blyth St, Cromwell, home early on Saturday. The vehicle was locked, but a nearby shed was broken into and the offenders found the ute key in the shed, Sgt Paget said.
The vehicle, which did not appear damaged, was found by a member of the public parked by the McNulty Inlet boat ramps about 8am on Saturday.
''The vehicle has been taken for a joyride, used off-road at times, and we believe it's travelled quite a distance, about 120km, and it appears to have been driven vigorously and at high speed, going by the amount of diesel used,'' he said.
Police wanted to hear from anyone who was driving from Wanaka, Queenstown or Alexandra to Cromwell between 1am and 8am on Saturday who might have seen the vehicle.
They also want to hear about sightings of the vehicle around Cromwell, suspicious activity around the Blyth St area, or vehicles being driven at high speed in that area early on Saturday.
Cash was taken from a wallet in the Mazda and a box of beer from the complainant's shed. Sgt Paget said police would speak to the complainant about leaving guns and ammunition in an unattended vehicle, as that was an offence under the Arms Act.
