Three men assaulted two other men before robbing them and one woman in Woodcroft on Sunday.
The robbery and assaults occurred at Woodcroft Lakes at about 8.40pm.
The two men, 22 and 18, and the woman, 25, had been sitting on a park bench when the woman and one of the men wandered away.
They told police they returned to the spot when they heard shouting and found their companion being confronted by three other men.
He was punched in the face and fell to the ground while his attackers stole his bag.
The three men then approached the woman and the other man, punched him and demanded money.
They handed some of their property to the men who then fled the scene.
Police said there were no clear descriptions of the men.