Police are investigating a small fire in grass on the Port Lincoln coastline on Monday afternoon.
Port Lincoln MFS and police were called to the scene just before 6pm after a passer by saw a small grass fire between the foreshore and the Lincoln Highway.
Two MFS appliances responded but on arrival found the fire had already been extinguished by residents.
Firefighters then performed a mop up with a total area of about 15 square metres of grassland burnt.
The MFS reports that a group of children were seen running from the area.
Police also report a blue cigarette lighter and burnt rag was found at the base of the fire.
Police are investigating and anyone with information who had seen suspicious behaviour in the area at that time are encouraged to contact Crime Stoppers on 1800 333 000.