An electrical fault is thought to have sparked a blaze that destroyed three truck units and a trailer worth $500,000.
The trucks and trailer were parked roadside in Beach Rd, Dargaville. Firefighters were called to the blaze about 12.45am yesterday.
Dargaville's Deputy Chief Fire Officer Michael Ross said all three rigs were well ablaze when they arrived and there was nothing that they could do but hose them down.
Fire investigator Craig Bain said although the truck parked in the middle was having its battery charged, some sort of electrical fault had started the fire that destroyed $500,000 worth of vehicles. It was not considered suspicious. He was continuing to investigate.