The nearest house, about 15m from the fire, was unoccupied and dampened with fire hoses as a precaution.
Mr Nichol said it was unsafe for firefighters inside the building and the decision was made to "surround and drown".
"We made use of our ladder truck - we were able to get up above and pour water on."
Neighbours were told to remain indoors and avoid breathing smoke.
Hurinui Anderson-Taueki said the fire was "big and scary".
"I just walked out my front door to see a huge fire," she said.
"That is one of the biggest fires there has ever been in Hawke's Bay."
Mr Nichol said the Fire Service waited for clearance from Napier City Council before opening the highway, to ensure the razed structure wasn't a public hazard.
"A lot of the walls have caved in - external and internal. Obviously there is a lot of loose iron there and with the wind up ..."
An investigation into the cause of the fire was ongoing.
"We don't know what has caused it. Obviously with a big fire like that a lot of the evidence has burned."
The property is owned by accountant John Davidson.
He said it had been unused since the paua farm ceased operating about three years ago.
The paua farming infrastructure was still in place and he had hoped to get it running again.
"It's a big loss - I'm still in a state of shock," he said.
At the time of going to print last night the highway was still closed to traffic.
Meanwhile two helicopters were called to Porangahau on Saturday after a forestry block caught on fire.
Central Hawke's Bay deputy principal rural fire officer Bruce Kitto said the 9.06am fire on Cooks Tooth Rd was caused after the property owner rested a scrub cutter on grass, which ignited when it made contact with the scrub cutter's hot exhaust.
"He tried to put it out himself but it kept flaring up and eventually got into the big pine forest - [the forest] looks to be about 20 years old," he said.
He said there was little wind "to cause major concern" for the fire, which burned up to 2ha of grass, scrub and forest.
"While it didn't do a great deal of damage to the trees, it burned through the thinnings and other stuff lying on the floor - it kept us busy for a few hours.
It was very difficult to get to and fight, because of how big it was and where it was."
The Fire Service was again called to the property on Sunday morning after the fire "popped up" after burning underground.