Firefighters are battling a large shed blaze on Crawford St in Hamilton.
The fire measures 30m by 20m and three fire trucks are at the scene, said Fire and Emergency shift manager Mau Barbara.
The fire service received "multiple" calls about the fire about 9.35pm this evening, Barbara said.
"On arrival, the building was well ablaze and we have called for more crews."
Three more fire trucks are expected at the scene from nearby stations, Barbara said.
Once they arrive, about 26 firefighters will be fighting the flames, he said.
There are no plans to evacuate nearby properties at this stage.
St John Ambulance and police have been advised of the fire.