Firefighters are still at the scene at Quality Foods Southland in Baker St, Rockdale.
A Fire and Emergency New Zealand spokeswoman said they were called to the blaze about 2.15pm.
It was then upgraded to a second alarm, a total of four firetrucks responding.
The main fire, located in a 20m x 30m compartment, had been extinguished and crews were currently going through the rest of the large building.
A fire investigator was also in attendance.
People on site were evacuated from the building but no evacuations were required of any further buildings in the area, the spokeswoman said.
A group of between 20 and 30 workers could be seen outside the building.
Firefighters are also currently responding to a ‘‘well-involved hedge and shed’’ fire in Invercargill.
The spokeswoman said initially 8 metres of shelterbelt was ablaze, but it had since spread to a 10m x 10m shed.
Three firetrucks were at the scene and a fourth was on its way.
