A business premises in the tiny hamlet of Narford was the target of catalytic converter thieves in the past week, police have said.
Six vehicles in the village had their converters stolen in the raid.
Police are urging motorists to be vigilant as the Narford thefts were part of a wave of catalytic converter thefts across the whole county since last Friday.
Three thefts also occurred in Dereham, one in Blofield, and one in Acle.
Officers are urging people to call police if they witness anyone acting suspiciously around vehicles, particularly around vans and pick-up trucks.
South Norfolk district commander, Chief Inspector Stuart Armes, said: “Catalytic converters are prime targets for thieves because they contain premium metals. I would urge drivers of 4x4s, pick-up trucks and vans, which seem to be a prime target, to be vigilant and take sensible measures.
“Officers are currently employing a number of tactics to identify and apprehend those responsible and we would be interested to hear from anyone who may have information.”
Officers have this advice to prevent becoming a victim of crime, including:
n Keep vehicles in a well-secured garage where possible, and if no garage is available, in a well-lit, public area.
n Vehicles can be parked in such a way as to make access to the catalytic converter difficult, or parallel with another vehicle if you own one.
n Commercial vehicles should also be kept in a locked building or compound.
n Use alarms, lighting and CCTV to deter thieves.
n Mark your catalytic converter - etching the part and spraying with heat-resistant paint. Contact your local crime reduction officer on 101 for more information.
Anyone who sees anything suspicious should contact Norfolk Constabulary on 101 (calls cost 15p) or call 999 if you believe a crime is in progress.