Police are appealing for information after several excavators were set on fire at a residential development site in St George Basin on Monday.
About 4am, emergency services were called to Creoea Road following reports of a fire.
NSW Rural Fire Service attended and extinguished the blaze.
Officers from South Coast Police District established a crime scene and began inquiries.
More than $250,000 worth of machinery and excavators were destroyed by the fire, which is being treated as suspicious.
South Coast Police District Acting Inspector Luke Geradts said police were disappointed by the incident.
"The machinery that was damaged is individually owned by local businesses, so it is a huge loss for members of our community," Acting Inspector Geradts said.
"We are appealing for anyone with information about the incident to come forward."
Anyone with information about this incident is urged to contact Crime Stoppers on 1800 333 000 or https://nsw.crimestoppers.com.au. Information is treated in strict confidence. The public is reminded not to report crime via NSW Police social media pages.