Police are investigating after a man was knocked unconscious outside a Hungry Jacks after allegedly being struck by rocks.

The altercation unfolded in the Mandurah suburb of Falcon, located in WA’s Peel region, after a 25-year-old man was approached by a group of unknown juveniles at about 4.30pm on Monday.

Police allege was was assaulted and struck by rocks, causing him to lose consciousness and fall to the ground.

St Jon Ambulance paramedics were called at 4.42pm and took him to Peel Health Campus under normal road conditions where he was treated for facial injuries.

Mandurah Police are investigating and no charges have been laid at this stage.

Members of the public with information or footage via CCTV, phone or dash cam is asked to contact Crime Stoppers.

Reports to Crime Stoppers can be made anonymously.