Four helicopters are currently fighting a vegetation fire between Springs Junction and Murchison.
The fire, which started around 11am on Monday, was initially covering four hectares of land but has since spread to 15 hectares in size.
Fire and Emergency shift manager Simon Lyford says a fourth helicopter has just arrived at the site of the fire, which is not yet contained.
"Initially we responded crews from Murchison and Springs Junction, who have since stood down due to the nature of the terrain, which is not helping."
He says the fire, on the edge of SH65 near Neilson Flat, has steep hills on both sides of the road.
A rural crew from Rotoiti is still on site assisting helicopter crews.
Initially crews put a helicopter on standby but it became clear as soon as they arrived that more than one would need to respond.
Simon says the "light wind" seemed to be "swirling around" but there were no reports of strong winds.
"One of our executives has also flown down on a helicopter from Blenheim," he says.
He says there are no buildings under threat.
SH65 was initially closed to allow road crews to respond but it has now been reopened to one-lane of traffic.
