A stray spark set the roof of a large commercial building alight and shrouded industrial Pandora in smoke on Monday.

Billowing smoke could be seen emitting from the Galvanising Hawke’s Bay building in Pandora, Napier, about 1.15pm.

General manager Scott Ryan said the business is currently in its annual maintenance period and there were repairs being carried out on Monday to prepare for opening next week.

“We were doing some repairs on one of the tanks, which was empty, and a welding spark ignited some insulation on the exterior of the tank which then caught on to the wall and moved up to the roof,” Ryan said.

A fire erupted at a commercial premises in Pandora, Napier, on Monday afternoon. Photo / Vaughan Miringaorangi

“We just literally put that roof back on last week so it is unbelievable.”

He said the damage was relatively minor luckily and they expect to be operating again within two weeks.

“Staff were fantastic, they exited and did what they were supposed to do, which was get out of the way and wait for the professionals to arrive.”

He said the smoke was no different from any other building fire and there was no risk of hazardous, toxic fumes from the burnt building.

Fire Emergency New Zealand (Fenz) central shift manager Chris Dalton said five fire appliances attended the significant fire at a galvanising factory at 1.15pm.

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Fire engines on the scene of the fire in Pandora, Napier, on Monday. Photo / Warren Buckland

He said it appeared the main blaze had been extinguished and firefighters were dampening down hotspots as of 1.50pm.

He said reports indicated everyone inside the building had gotten out safely.

A St John spokesperson confirmed St John sent an ambulance but said they were not required.

A police spokesman said police received reports of the fire at 1.15pm.

Firefighters had extinguished the main blaze by 2pm and were dampening hotspots. Ambulance staff attended but were not required. Photo / Warren Buckland

The spokesman said traffic diversions were in place in the area while firefighters dealt with the blaze.