One of the country's oldest department stores escaped extensive damage when a sprinkler system activated and put out a fire which could have destroyed the building.

The Fire Service said without the sprinkler system the historic Smith and Caughey's store in Auckland's Queen St could have been destroyed last night.

Ten fire appliances attended the blaze and firefighters broke a window to get in shortly before 11pm.

They found a fire among some electrical appliances near a lift but Fire Safety Officer Ray Coleman, said it was beneath a sprinkler head and when that sprinkler was activated the fire was virtually extinguished.

"Although we have got a reasonable bit of fire damage we ended up with more water damage."

He said it showed the value of a sprinkler system in a fire.

"If the sprinkler system had not actuated or conversely they did not have a sprinkler system we would have had a far more serious fire than we've got. The sprinkler system has been the saving grace."

"How often do we say if they had had this, if they had had that... well here we are with a building that had a sprinkler system and the proof is in the pudding."

The fire was thought to have been started by an electrical fault but Mr Coleman said the store was likely to open for business today.

"We cleaned it out quite a bit last night and pumped out quite a bit of smoke. It is not too bad."

Fire damage was confined to a till area and two storage areas which could easily be cordoned off for the opening of business.

Smith and Caughey's was founded in 1880 when Marianne Smith opened a drapery store. It has been in Caughey family ownership for 128 years.