A small fire at the Marsden Point oil refinery was extinguished within minutes, a refinery spokesman said.
However, 10 crews from Whangarei, Ruakaka, Waipu and Portland responded to the fire, with the last crews leaving about 10.30pm.
Refining NZ's Greg McNeill said the Marsden Point refinery emergency services team extinguished a small fire on a crude furnace at about 3pm on Saturday.
"The fire was quickly isolated and put out within a matter of minutes, without injury to refinery staff or the emergency services crew," Mr McNeill said.
The blaze is believed to have broken out in Building A after crude oil had leaked on to the ground from a furnace tube, a fire communications spokesman said.
Mr McNeill said while repairs would be required, the minor nature of the incident meant there was no impact on the country's fuel supplies.