About $10,000 worth of damage has been done to buildings at Koonoomoo Recreation Reserve.
Cobram police Senior Constable Amy McColl said two buildings were broken into and extensively vandalised some time between 3pm on Saturday, July 1, and 8.30am on Sunday, July 2.
She said all the windows were broken, two roller doors were damaged, tables were flipped, barbecues damaged and the fire extinguisher was let off.
According to police, Moira Shire Council is estimating the damage to be roughly worth $10,000, which includes damage to all the windows as well as two roller doors.
Police are appealing for help from anyone who saw or heard anything suspicious. They should call Cobram police on 58712866 or Crime Stoppers on 1800 333 000 or crimestoppersvic.com.au