Helicopters are on their way to a scrub fire in a remote South Island mountainous region near Arthur's Pass.
Emergency services started getting calls about the blaze on Mt Horrible at 2am.
A Fire Service spokeswoman said crews were not able to reach the fire by road and helicopters were expected to arrive at first light.
At present there is no threat to people or property.
A stretch of road on State Highway 73 had been closed between Cass and Bealey.