A man is in hospital and police are investigating after an incident at the Casuarina Sands reserve at Stromlo on Sunday evening.
Police said they were called to the scene after reports of a non-responsive 20-year-old man.
He treated by paramedics and taken to Canberra Hospital.
Police are now calling for witnesses to the incident.
No one else is believed to have been involved at this stage and police could not provide any further details as investigations continue.
Anyone with information is urged to contact police on 131 444 or Crime Stoppers on 1800 333 000, quoting reference number 6225115
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