Richard and Alison Anderson, of Cresslea, on Ida Valley Back Rd, were woken by explosions about 6am yesterday. The woolshed near their home was on fire and they called emergency services.
Omakau volunteer firefighters responded with an appliance and water tanker about 6.15am, but the woolshed was fully involved before they arrived.
Southern region fire safety officer Barry Gibson, of Dunedin, examined the site yesterday.
He said the fire was not suspicious, but it was too early to determine where and how it started.
The Andersons were probably woken by the sound of exploding tyres on a tractor parked in a covered stock yard against the woolshed wall, Mr Gibson said.
The blaze was hot enough to bend the steel roof beams of the 10m by 20m woolshed, which collapsed inwards.
Bales of wool in one corner of the shed were burnt, and a wool press destroyed.
Some diesel for farm use had been stored in the shed, as well as a container of oil.
''That would have helped feed the fire. There were high winds yesterday and a lot of rain last night, which are factors being taken into consideration to determine the cause,'' Mr Gibson said.
The Andersons praised the response of Omakau firefighters but declined to comment further yesterday.
