Three 12-year-old boys will be dealt with under the Young Offenders Act, following two separate deliberately lit fires in the Illawarra.
About 10.20am on Sunday, the NSW Rural Fire Service responded to a grass fire in the reserve south of Gilba Road, Koonawarra.
The fire was extinguished shortly after.
Lake Illawarra Police District officers attended the scene and began an investigation into the source of the fire.
Following inquiries, two boys, aged 12, were spoken to by police and will attend a youth conference under the Young Offenders Act for the offence of cause bushfire.
About 12.15pm, police were called to a small fire on a bridge behind a sporting club on McGregor Avenue, Warilla.
The fire was extinguished by members of the public shortly after it was allegedly lit.
Police attended and spoke with a 12-year-old boy, who will be issued with a caution under the Young Offenders Act.
Lake Illawarra Police District Inspector Brian Pedersen said the number of deliberately lit fires across the district is a concern for police.
"It's quite distressing to see young people in particular continuing to ignore the message about how dangerous fires can be," Insp Pedersen said.
"We are urging the whole community to be vigilant and report any suspicious behaviour.
"Information provided to police from members of the public can help us identify and suppress fire-bugs before they start lighting.
"I want to urge members of the community - if you see something, say something."
Anyone with information about suspicious fire activity is urged to contact Lake Illawarra police or Crime Stoppers on 1800 333 000.