Up to 40 firemen battled for more than two hours to save Greymouth's historic Railway Hotel last night.
Fire crews from the neighbouring Cobden, Runanga and Brunner brigades combined with three Greymouth Volunteer Fire Brigade units to fight the blaze in the upstairs guests'.
Greymouth fire chief Alan McEnaney said it was "hot and dangerous work".
The first appliances arrived on the scene at 10.45pm and were still fighting the fire at 1am today.
"It looks like it started in an electrical point in a wall socket in the manager's flat and moved into a false ceiling, which was little more than a foot high, spreading from there," Mr McEnaney said.
"It was too windy for us to get in from the roof so we had to enter from the gables and break through the first ceiling to attack it."
Hotel staff said it was fortunate gangs of visiting builders and painters, who had been staying at the hotel, had headed home for the weekend.
Only one of the guest rooms was occupied when a staff member noticed smoke. Other staff members kicked in the door to the manager's room and immediately called 111 when they saw the extent of the blaze.
Owner Grant Olsen said this morning he was hoping to have the bar up and running again later today.
"It's up to the fire department. I really can't do anything until they give me the all clear. "I have to thank all the fire officers and police. They did a fantastic job of saving the old girl (the hotel), and Kim (Sims) the manager, and staff did a great job of getting everyone out."
The fire caused extensive damage.