Senior Sergeant Anthony Bond, of Dunedin, said the contractor arrived at the tavern to clean the fryers early this morning.
The contractor turned the fryers on, went outside to get further gear from his van, and upon his return noticed smoke and flames.
He turned everything off, went back outside and called 111, Snr Sgt Bond said.
A fire investigator was on the scene after the Caversham pub suffered extensive damage when fire tore through the kitchen and roof.
Initial fears a person was trapped were allayed when the individual was located soon after 4am, the spokesman said.
Staff and patrons have been left "heartbroken" and "absolutely gutted".
Dunedin Central Fire Station senior station officer Ant O'Neill said crews arrived to a well-established kitchen fire about 3.50am.
The first crews to arrive put on breathing apparatus and rushed inside to attack the blaze, SSO O’Neill said.
However, minutes after entering the building, the ceiling tiles started to fall in and the roof collapsed, forcing the firefighters out of the building and refocusing the attack from outside.
It took around 30 minutes for crews to get the fire under control and ‘‘mop up’’, ensuring it was out, and checking for hotspots began.
The cause was as yet unknown, but there was extensive damage to the roof as well as smoke and water damage throughout the building.
‘‘There is a lot of damage,’’ SSO O’Neill said.
About 7.30am today, two firefighters were hosing down the building inside and outside.
Tables and chairs were stacked inside and large sections of the roof were gone. Scorch marks and smoke damage was evident around a window on the second floor at the rear of the building.
Fire and Emergency New Zealand (Fenz) spokesman Simon Lyford said after a 3.52am emergency call, crews from Lookout Point and St Kilda responded.
They could see flames and smoke on their way to the fire and immediately put out a second alarm, and appliances from Dunedin Central and Roslyn also began rolling.
About 4.05am there were possible reports someone was missing, but about 10 minutes later everyone was accounted for, Mr Lyford said.
The fire was about 20m by 20m when firefighters began attacking the fire externally, he said.
The fire was reported ‘‘knocked out’’ by 4.55am.
Crews would be on site throughout the morning, he said.
A post to the tavern’s Facebook page said staff was ‘‘absolutely gutted ’’ and the pub would be closed ‘‘for some time’’.
It prompted an outpouring from ‘‘heart-broken’’ and ‘‘gutted’’ patrons, who wished staff and the tavern’s management well.
Lance Patterson said he and his wife had their wedding reception there ‘‘and the place brings back so many fond memories’’.
Lisa Hall said the tavern had been ‘‘all our girls’ go-to place for dinner and a catch-up’’.
‘‘We all are thinking of you all there and sending much love and hugs your way.’’
