A truck company office worker told of ground-shaking explosions as three separate fires broke out at Thurgoona on Tuesday afternoon.
One was reported around Racecourse Road, another at Meander Street and a third at the southern end of Elizabeth Mitchell Drive.
All swept across grassland amid 35-degree heat.
Hehir's Transport employee Sue Collins, whose workplace is in Ceres Drive near Racecourse Road, was "quietly" doing tasks when the alarm was raised by a man entering the office.
"About a minute-and-half later he came running back and said I think you better get out," Ms Collins said.
"Flames were just all around us, behind us, beside us, either side."
Ms Collins said bangs from nearby businesses told of the fire's impact.
"There was quite a few explosions, I think there is a lot of business down that way so we don't know, could be gas bottles, tyres anything," she said.
"Massive explosions, probably about five or six.
"It could be gas bottles, there all factories around here, so anything's possible.
"It actually shook the ground."
Fellow business at the site CMTP faced the loss of some crates and timber due to the fire, with the firm's Michael Yeats using a hose in a desperate bid to stop flames entering the yard.
"At that time I couldn't give a toss about the timber, I was more worried about the people that were fighting the fires and making sure I wasn't in their way," Mr Yeats said.
"It's hard to describe, you actually have to physically be there."
RFS district co-ordinator Andrew Gray said homes had been threatened by the fires, but quick work of crews saved them.
However, some vehicles in storage were reported to be damaged.
Mr Gray said the cause of the blazes would be investigated by police and the two NSW fire services as they covered areas serviced by both of the emergency organisations.
He said it was "concerning" given the weather there had been three ignition points.
The RFS had more than 20 tankers with 60 personnel, Fire and Rescue supplied five tankers with a total crew of 20 and the CFA contributed four tankers with 16 members.