Blenheim Rural Fire controller Richie Law said one firefighter suffered smoke inhalation and another had sustained suspected broken ribs.
It is understood that a firefighter was hurt in a fall.
Law said changeable winds had turned back towards firefighters.
Fire Service southern communications shift manager Andrew Norris said the fire changed course about 5pm.
It had been burning downhill in a northwesterly until a southerly wind shift drove it back uphill, making it more challenging for firefighters.
He said all residents were evacuated and nobody was unaccounted for. "A couple have been taken out by helicopter."
They had gathered in the small settlement of Hakahaka Bay, just over 2km away.
Picton residents Nadine Taylor, husband Graham Taylor and son Nick were returning to Port Underwood after a day crayfishing on their commercial vessel The Fugitive when they saw the fire rising in front of them and the fire appliances racing towards it.
Nadine Taylor said the blaze towered over a house.
"There were shafts of flames off pine trees reaching into the sky so it was pretty obvious that the houses were likely to go," she said.
"The smoke was incredibly thick. The flames were leaping. The smoke had that amazing orange colour that it is when it's got huge flames underneath it."
She said the fire moved swiftly in the gusty northwest wind and quickly threatened eight to 10 houses on a peninsula.
The Taylors scouted along close to the coastline checking for residents, but saw none.
Sam Jorgensen was also out fishing when he saw smoke and flames in the bush above.
"We could see a small house close to the fire but couldn't actually see if it was a house or trees on fire," he said.
"There was a lot of smoke and it was pretty much engulfed in flames."
Trevor and Dawn Rhodes were evacuated from their home at 6.30pm as a precaution.
"Our place is all right at the moment but the properties in Hakahaka Bay are in danger so they are evacuating us for safety's sake," Dawn said, before leaving her house.
- additional reporting by Rebecca Quilliam of APNZ