Two girls have been charged with deliberately lighting a grass fire in Sydney's west.
As families across NSW counted the cost of the devastating bushfires that have already razed 200 homes, police allege the girls - aged 12 and 13 - were spotted lighting fires in a reserve at Bonnyrigg.
Officers went to the reserve, which runs between Elizabeth Drive and Smithfield Road, shortly before 1pm (AEDT) on Friday and saw two girls running away.
Police helped Fire and Rescue NSW contain a blaze covering up to 30 square metres.
A short time later, two girls were arrested at a nearby business and questioned at Fairfield Police Station.
They were released pending further inquiries before being charged on Saturday with causing or setting fire to property.
They are due to appear in the Children's Court on December 4.
Premier Barry O'Farrell slammed the girls' alleged actions as "sheer stupidity".
"It is absolutely disappointing that we have a report of two people allegedly seeking to light fires," Mr O'Farrell told reporters at Wyong Rural Fire Service (RFS) headquarters on Saturday.
"But what's great about this incident is that the public has done exactly what the authorities want them to do; they've seen suspicious activity and rung police or RFS.
"It's just sheer stupidity, sheer recklessness, but out of it a great example of the community being alert."
Police want to speak to witnesses, including those who talked to officers at the scene but did not give a formal statement.