A spot fire which burned out the southern end of Brushabers Road, south of Jennings, on Tuesday night and breached containment lines to cross the New England Highway towards Sunnyside is evidence that those in the fire zone need to remain vigilant, RFS spokesperson Paul Best said.
He said the dryness of the fuel is allowing spotfires to start easily and spread quickly.
"Even in blackened areas there are still pockets of vegetation, and it doesn't take much for fires to flare up."
Windy conditions on the night caused the fire rating to climb to a 'watch and act', blowing the outbreak across containment lines.
"The threat eased after an hour," Mr Best said.
Quick action by ground crew -- aided by rigorous waterbombing before aircraft were due to finish for the day -- wrapped up the outbreak quickly.
Heavy machinery was used overnight to build new containment lines farther west of the fireground, with work continuing on Wednesday to fully-extinguish the blaze.
Some backburning is also planned, depending on weather conditions.
On Wednesday morning passersby witnessed a truck carrying earthmoving equipment with its cabin alight on the highway in the same area, but Mr Best said this was unrelated to firefighting efforts.
The driver was just fortunate there were plenty of firefighters on hand to put out the blaze.