Three people have been arrested for deliberately starting a fire at Shalvey in western Sydney on Tuesday afternoon.
Five police crews worked with the RFS to find the juveniles after the fire burned for more than two-and-a-half hours.
Deputy Commissioner Mick Fuller says it is a disgraceful act.
"It's important the community know that we're out there working with the RFS closely to make sure that we arrest anyone who's conducting this type of activity," he says.
Elsewhere in New South Wales, Illawarra police have arrested a man for breaching the total fire ban.
Police were called to the 70-year-old's rural property at Wongawilli early on Tuesday and saw a fire being used for stove cooking in a carport.
They say the stove was old and damaged and hot ash was falling to the ground.
The man was arrested after he repeatedly tried to prevent officers from extinguishing the fire.