Justin Ashwell was on the scene not long after the fire had started and said there was little which could have been done to stop it.
Due to incredibly dry conditions caused by hot temperatures throughout the Canterbury region last week, trees and grass in the area were quickly engulfed.
Meanwhile, two helicopters have been dispatched in North Otago to battle a large fire on Broken Hut Rd, near Omarama this afternoon.
However, both helicopters were temporarily grounded after a drone was spotted flying in the proximity.
A person close to the operation said the helicopters were grounded for about 20 minutes and police had been notified.
Neither the drone nor its operator had been found, they said.
The helicopters were deployed to help battle the large blaze in Broken Hut Rd, south of Omarama, which sparked about noon.
Fire crews were first alerted to the blaze around 120km west of Oamaru around 12.20pm and about 20 firefighters are on the scene.
FENZ shift manager Andrew Norris said crews from Omarama, Twizel and Kurow were struggling to contain the blaze, which had destroyed a hay barn and spread to surrounding trees.