A fire ''erupted'' at The Bog Irish Bar in Dunedin last night.
Dunedin City fire station senior station officer Jason Hill said firefighters were called after an alarm activated at the bar on the corner of London and George Sts at 7pm.
The crew arrived two minutes later, the patrons having been evacuated, and initially saw no signs of any fire.
Firefighters entered the building, and when a second crew arrived, they saw smoke billowing from three windows of a 20m by 20m office on the first floor.
''Then the fire erupted out several windows on the first floor,'' Mr Hill said.
The fire was under control in 20 minutes, he said.
The fire had ''completely gutted'' the first floor office and the floor below was water damaged, including the kitchen and bar.
During the fire, 18 firefighters attended in five trucks, he said.
East Otago Southland fire risk management officer Cathy Trevathan said the cause had not been determined and the possibility the fire was suspicious had not been discounted.
Fish Hook owner Mike Trewern said he saw 6m flames licking out of three windows in London St and ''it was quite spectacular''.
He believed the office was above the bar's kitchen.
''They [the firefighters] got there in the nick of time before it got a hold,'' Mr Trewern said.
