Wellington police are on the hunt for men who allegedly ran up to a train on the tracks, apparently to start tagging it.
On December 19, say police, the men ran up to the passenger train in Upper Hutt, while it was stationary. They then caused "extensive damage" to the train.
The police have now taken to Facebook to appeal for help identifying the men, who were photographed in the act by outraged passengers.
The police spokesperson said the men's actions were not only illegal, but also "highly dangerous".