School staff noticed what appeared to be blood in a cubby house in the children’s playground last Tuesday, January 31.

Police were called and a crime scene set up.

Samples were taken for forensic examination and test results have confirmed the blood is human.

DNA testing is now underway in an effort to identify a potential victim.

Strike Force Laundry has been formed to investigate and comprises Detectives from Campsie Local Area Command.

Police are concerned that someone may have been injured during an incident in the playground.

Checks with local hospitals have so far have failed to link any people seeking treatment to the scene.

The incident is believed to have happened during the school holidays and police said there was no evidence that the incident was connected with any staff or students at the school.

They are appealing for anyone who may have seen people in the playground of the public school in Union or Mary Street, Riverwood between January 13 to 29 to come forward.

Contact Campsie Police or Crime Stoppers on 1800 333 000.